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Title: Rust, Smut, Mildew, & Mold
Author: Cooke, M. C. (Mordecai Cubitt)
Language: English
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                      RUST, SMUT, MILDEW, & MOULD.



------------------------------------------------------------------------



                                LONDON:
                          GREAT QUEEN STREET,
                       LINCOLN’S-INN FIELDS, W.C.



------------------------------------------------------------------------


[Illustration:

  Plate VII.
  W. West imp.
]


------------------------------------------------------------------------


                      Rust, Smut, Mildew, & Mould.


                         ---------------------



                      AN INTRODUCTION TO THE STUDY


                                   OF


                           MICROSCOPIC FUNGI.



                                   BY


                              M. C. COOKE,

     AUTHOR OF “A PLAIN AND EASY ACCOUNT OF BRITISH FUNGI,” “INDEX
         FUNGORUM BRITANNICORUM,” “A MANUAL OF BOTANIC TERMS,”
                 “A MANUAL OF STRUCTURAL BOTANY,” ETC.



                             Third Edition,
               WITH NEARLY 300 FIGURES BY J. E. SOWERBY.



                                LONDON:
                   ROBERT HARDWICKE, 192, PICCADILLY.
                                 1872.


------------------------------------------------------------------------



                          BY THE SAME AUTHOR.

THE BRITISH FUNGI: A Plain and Easy Account of British Fungi: with
especial reference to the Esculent and other Economic Species.
Illustrated with Coloured Plates of 40 Species. 2nd Edition. Fcap. 8vo.,
price 6s.

“The author is a thorough mycophagist, well acquainted with the peculiar
features by which the most remarkable of the edible kinds of Fungi may
be known.”—GARDENERS’ CHRONICLE.

“A very readable volume upon the lowest and least generally understood
race of plants. For popular purposes the work could not have been better
done.”—ATHENÆUM.

                                -------

INDEX FUNGORUM BRITANNICORUM: A Complete List of Fungi found in the
British Islands to the Present Date. Arranged so as to be applicable
either as a Check-List or for Herbarium Labels. Royal 8vo., price 2s.
6d.

  Also the same Work, printed on only one side, for Herbarium Labels.
   Part I. HYMENOMYCETES, 1s. Part II. GASTEROMYCETES, CONIOMYCETES,
            and HYPHOMYCETES, 1s. Part III. ASCOMYCETES, 1s.

                             --------------

               London: ROBERT HARDWICKE, 192, Piccadilly.



------------------------------------------------------------------------



                       PREFACE TO SECOND EDITION.


THE first edition of this Work having for some time been out of print,
and the demands of the public encouraging the publisher to proceed with
a new edition, I have added, in a second Appendix, descriptions of all
the species discovered in Britain since 1865, so far as they relate to
the Orders included in this volume. The success which has attended the
sale of this Work, and the number of fresh observers it has brought into
the field, has greatly tended to the necessity for a second Appendix. A
larger number of observers, over a still more extended area, will, it is
hoped, add further to our list; by increasing the number of known
species. Hitherto one great cause of the paucity of students of Fungi in
this country, especially of the Microscopic forms, has been the want of
text-books on the subject, containing descriptions of the species, with
figures illustrative of the genera. Although this little volume only
partly supplies that want, by including the species found on living
plants alone, it has already proved of service; this and its companion
volume, “Introduction to British Fungi,” being (with but one exception)
the only books on Fungi which have passed into a second edition in this
country; a fact which appears to prove that they have succeeded in
furnishing a desideratum, and in giving an impetus to the study. It is
hoped that similar results will follow the publication of this new
edition.

                                                            M. C. COOKE.


------------------------------------------------------------------------



                               CONTENTS.


             CHAP.                                      PAGE

                I. CLUSTER-CUPS                            1

               II. SPERMOGONES                            22

              III. DI-MORPHISM                            33

               IV. MILDEW AND BRAND                       45

                V. COMPLEX BRANDS                         67

               VI. SMUTS                                  77

              VII. COMPLEX SMUTS                          90

             VIII. RUSTS                                  95

               IX. RUSTS (continued)                     110

                X. WHITE RUSTS                           124

               XI. MOULDS                                138

              XII. WHITE MILDEWS OR BLIGHTS              162

             XIII. SUGGESTIONS                           179

                   APPENDIX, CLASSIFICATION, AND         189
                     DESCRIPTIONS OF FUNGI CONTAINED
                     IN THIS VOLUME

                   APPENDIX II.                          223

                   Index                                 239


------------------------------------------------------------------------



                           MICROSCOPIC FUNGI.

                                -------



                               CHAPTER I.

                            _CLUSTER-CUPS._


IN these latter days, when everyone who possesses a love for the
marvellous, or desires a knowledge of some of the minute mysteries of
nature, has, or ought to have, a microscope, a want is occasionally felt
which we have essayed to supply. This want consists in a guide to some
systematic botanical study, in which the microscope can be rendered
available, and in which there is ample field for discovery, and ample
opportunity for the elucidation of facts only partly revealed. Fungi,
especially the more minute epiphyllous species, present just such an
opportunity as many an ardent student would gladly take advantage of;
one great obstacle to the pursuit being hitherto found in the absence of
any hand-book to this section of the British Flora, embracing the
emendations, improvements, and additions of the past twenty-seven years
(the period at which the fifth volume of the “English Flora” made its
appearance). It would be incompatible with our object, and beyond our
limits, to introduce an entire mycological flora to our readers in these
pages; but we hope to communicate such information as will serve to
prepare the way still more for such an additional Flora, should it ever
be produced, and render the demand still wider and more general for such
an extension of our botanical literature. It is true that one work has
of late years issued from the press on this subject, but notwithstanding
its utility to scientific men as a record of species, it is practically
useless to those we address, from the absence of all specific
descriptions of microscopic fungi.

Let not the reader imagine, from what we have just stated, that it is
our intention to burden him with a dry series of botanical descriptions;
as much of this as we deem essential to render the book available to the
botanical student, we have preferred to add in the form of an Appendix.
Useful as these may be to some, we hope to be enabled to furnish for
others something more; and although we at once disclaim any intention of
including all the microscopic, or even the epiphytal fungi, in our
observations, yet we trust, by a selection of common and typical species
for illustration, and by an adherence to certain well-defined groups and
sections, to demonstrate that the microscopist will find an eligible
field for his observations in this direction, and the botanical student
may gain some knowledge of their generic and specific distinctions.

It is exceedingly difficult to give a logical definition of what
constitutes a fungus. It is no less difficult to furnish a popular
description which shall include all and nothing more. If, for example,
we particularize the spots and markings on the leaves and stems of
herbaceous plants, so commonly met with from early spring till the fall
of the last leaf, and even amongst the dead and decaying remains of the
vegetation of the year, we may include also such spots and marks as
result from insect depredations or diseased tissue. It is not always
easy, with a cursory observation under the microscope, to determine
whether some appearances are produced by fungi, insects, or organic
disease: experience is the safest guide, and until we acquire that we
shall occasionally fail.

If we take a stroll away from the busy haunts of men, though only for a
short distance,—say, for example (if from London), down to New
Cross,—and along the slopes of the railway cutting, we shall be sure to
find the plant called the goatsbeard (_Tragopogon pratensis_) in
profusion. In May or June the leaves and unopened involucres of this
plant will present a singular appearance, as if sprinkled with
gold-dust, or rather, being deficient in lustre, seeming as though some
fairy folk had scattered over them a shower of orange-coloured chrome or
turmeric powder. Examine this singular phenomenon more closely, and the
poetry about the pixies all vanishes; for the orange powder will be seen
to have issued from the plant itself. A pocket lens, or a Coddington,
reveals the secret of the mysterious dust. Hundreds of small orifices
like little yellow cups, with a fringe of white teeth around their
margins, will be seen thickly scattered over the under surface of the
leaves. These cups (called _peridia_) will appear to have burst through
the epidermis of the leaf and elevated themselves above its surface,
with the lower portion attached to the substratum beneath. In the
interior of these cup-like excrescences, or _peridia_, a quantity of the
orange-coloured spherical dust remains, whilst much of it has been shed
and dispersed over the unoccupied portions of the leaves, the stems, and
probably on the leaves of the grass or other plants growing in its
immediate vicinity. These little cups are fungi, the yellow dust the
spores,[1] or ultimate representatives of seed, and the epiphytal plants
we have here found we will accept as the type of the group or order to
which we wish to direct attention (Plate I. figs. 1-3).


[Illustration:

  Plate I.
  W. West imp.
]


Footnote 1:

  Protospores they should be called, because, in fact, they germinate,
  and on the threads thus produced the true spores, or fruit, are borne.

Amongst the six families into which fungi are divided, is one in which
the spores are the principal feature, as is the aurantiaceous dust in
the parasite of the goatsbeard. This family is named _Coniomycetes_,
from two Greek words, meaning “dust-fungi.” This group or family
includes several smaller groups, termed orders, which are analogous to
the natural orders of flowering plants. Without staying to enumerate the
characteristics of these orders, we select one in which the spores are
enclosed in a distinct peridium, as in our typical plant they are
contained within the cups. This order is the _Æcidiacei_, so called
after _Æcidium_, the largest and most important of the genera included
within this order.

The _Æcidiacei_ are always developed on living plants, sometimes on the
flowers, fruit, petioles, or stems, but most commonly on the leaves:
occasionally on the upper surface, but generally on the inferior. The
different species are distributed over a wide area; many are found in
Europe and North America, some occur in Asia, Africa, and Australia.
When the cryptogamic plants of the world shall have been as widely
examined and as well understood as the phanerogamic plants have been, we
shall be in a better position to determine the geographical distribution
of the different orders of fungi. In the present incomplete state of our
knowledge, all such efforts will be unsatisfactory.

But to return to the goatsbeard, and its cluster-cups. The little fungus
is called _Æcidium tragopogonis_, the first being the name of the genus,
and the last that of the species. Let us warn the young student against
falling into the error of supposing because in this, and many other
instances, the specific name of the fungus is derived from the plant, or
one of the plants, upon which it is found, that therefore the species
differs with that of the plant, and that, as a rule, he may anticipate
meeting with a distinct species of fungus on every distinct species of
plant, or that the parasite which he encounters on the living leaves of
any one plant is _necessarily_ specifically distinct from those found on
all other plants. One species of _Æcidium_, for instance, may hitherto
have been found only on one species of plant, whereas another _Æcidium_
may have been found on five or six different species of plants. The
mycologist will look to the specific differences in the parasite without
regard to the identity or distinctness of the plant upon which it is
parasitic.

Before the _Æcidium_ breaks through the epidermis, the under surface of
the leaves of the goatsbeard will appear to be covered with little
elevations or pustules, paler at the apex; these soon become ruptured,
and the fungus pushes its head through the opening, at the same time
bursting by radiating fissures. The teeth thus formed resemble those of
the peristome of some mosses. All around the orifice of the peridium the
teeth become recurved, and the orange spores are exposed, crowded
together within. At first, and while contained within the peridium,
these spores are concatenate or chained together, but when dispersed
they are scattered singly about the orifice, often mixed with the
colourless cells arising from the partial breaking up of the teeth of
the peridium.

Let us pause for a moment in our examination of the individual cups, to
ascertain their manner of distribution over the leaves. In this instance
they are scattered without any apparent order over the under surface,
but generally thickest towards the summit of the leaves; occasionally a
few are met with on the upper surface. Sometimes two or three touch at
the margins, but we have never met with them truly confluent; generally
there is a space greater than the width of the cups around each, the
stratum or subiculum from whence they arise is scarcely thickened, and
there are no spots or indications on the opposite surface. If a leaf be
taken fresh and the cuticle stripped off, which it will sometimes do
very readily, the orifices through which the _Æcidium_ has burst will
appear in irregular holes. If a section be made of one or two of the
fungi _in situ_, they will be seen to spring from beneath the cuticle,
the peridium to be simple, and rounded at the base, the spores clustered
at the bottom, and the fringe to be a continuation of its cellular
substance.

The spores in this species are orange, subglobose, sometimes angular,
and indeed very variable both in size and form, though the majority are
comparatively large. Each of these bodies is, doubtless, capable of
reproducing its species, and if we compute 2,000 cluster-cups as
occurring on each leaf, and we have found half as many more on an
ordinary-sized leaf, and suppose each cup to contain 250,000 spores,
which again is below the actual number, then we shall have not less than
five hundred millions of reproductive bodies on one leaf of the
goatsbeard to furnish a crop of parasites for the plants of the
succeeding year. We must reckon by millions, and our figures and
faculties fail in appreciating the myriads of spores which compose the
orange dust produced upon one infected cluster of plants of
_Tragopogon_. Nor is this all, for our number represents only the actual
protospores which are contained within the peridia; each of these on
germination may produce not only one but many vegetative spores, which
are exceedingly minute, and, individually, may be regarded as embryos of
a fresh crop of cluster-cups. And this is not the only enemy of the kind
to which this unfortunate plant is subject, for another fungus equally
prolific often takes possession of the interior of the involucre wherein
the young florets are hid, and converts the whole into a mass of
purplish black spores even more minute than those of the _Æcidium_, and
both these parasites will be occasionally found flourishing on the same
plant at the same time (Plate V. figs. 92-94).

Naturally enough, our reader will be debating within himself how these
spores, which we have seen, are shed in such profusion, can enter the
tissues of the plants which give subsequent evidence of infection; in
fact, how the yellow dust with which the goatsbeard of to-day is covered
will inoculate the young plants of next year. If one or two of these
spores are sprinkled upon the piece of the cuticle which we have
recommended to be removed from the leaf for examination, it will be seen
that they are very much larger than the stomata or breathing-pores which
stud the cuticle: hence it is clear that they cannot gain admittance
there. There remains but one other portal to the interior of the
plant—namely, the spongioles, or extremities of the roots. Here another
difficulty arises; for the spores are as large as the cells through
which they have to pass. This difficulty may be lessened when we
remember that what are termed the spores which are discharged from the
cups are not the true spores, but bodies from which smaller seed-like
vesicles are produced; yet, even then there will be much need of an
active imagination to invent hypotheses to cover the innumerable
difficulties which would encounter their passage through the vessels of
the infected plants. The Rev. M. J. Berkeley proved many years ago that
the spores of bunt, for example, may be caused to infect all the plants
the seeds of which had been placed in contact with them; but this
affection did not necessarily accrue from the absorption of the spores,
or the ultimate sporidia produced after three or four generations. It is
possible that the granular or fluid contents of the spores may be
absorbed by the plant, and as a result of this absorption, become
inoculated with the virus, which at length breaks out in fungoid
growths. Much has been done to elucidate this mystery of inoculation,
but much also remains a mystery still. There is no doubt that the
inoculation takes place at an early age,[2] probably in the seeds of
many plants; in others it may be conveyed with the moisture to the
roots; but the spores themselves have certainly not yet been traced
traversing the tissues of growing plants.

Footnote 2:

  Dr. de Bary has lately shown that in many similar instances the
  seed-leaves are inoculated. It will be necessary to refer more
  particularly to his experiments hereafter.

If, instead of going in search of goatsbeard and its attendant fungus,
we turn our steps northward and enter one of the Highgate or Hampstead
woods, where the pretty little wood-anemone (_Anemone nemorosa_)
flourishes abundantly, and turn up the radical leaves, one by one, and
examine their under-surfaces, we shall at length be rewarded by finding
one covered with similar cluster-cups to those we have been describing
as occurring on the goatsbeard, but far less commonly. Leaf after leaf
will be found covered with the brown spots of another fungus called
_Puccinia anemones_, with which nearly every plant will be more or less
infected in the spring of the year; and at length, if we persevere, the
anemone cluster-cup (_Æcidium leucospermum_) will be our reward (Plate
I. figs. 4-6). The specific name will suggest one point of difference
between the two fungi, as in this instance the spores are white, and
somewhat elliptic. Probably this species is not common, as we have found
it but seldom, though often in search of it. A nearly allied species has
been found on _Anemones_ in gardens, having but few large teeth about
the orifice, though not constantly four, as the name would indicate (_Æ.
quadrifidum_).

A walk through almost any wood, in the spring of the year, will reward
the mycologist with another cluster-cup (_Æcidium_), in which the
peridia are scattered over the whole surface of the leaf. This will be
found on the wood spurge, giving a sickly yellowish appearance to the
leaves, on the under surface of which it is found. By experience one may
soon learn to suspect the occurrence of parasites of this nature on
leaves, from the peculiar exhausted and unhealthy appearance which they
assume as the spores ripen, and which will spare the labour of turning
over the leaves when there are no distinct spots on the upper surface.
_Æ. Euphorbiæ_ is found on several species of _Euphorbium_ or spurge,
but we have always found it most abundantly on the wood spurge in the
Kentish woods between Dartford and Gravesend. The spores in this species
are orange, and externally it bears considerable resemblance to the
goatsbeard cluster-cup, but the spores are rather smaller and paler, the
teeth are less distinct and persistent, the subiculum is more thickened,
and the peridia are more densely crowded.

There is another group of species belonging to the same genus of fungi
in which the arrangement of the peridia is different. One of the first
of our native wild flowers, in making its appearance after the departure
of frost and snow, is the little yellow celandine (_Ranunculus
ficaria_).

                  “Ere a leaf is on the bush,
                   In the time before the thrush
                   Has a thought about her nest,
                   Thou wilt come with half a call,
                   Spreading out thy glossy breast
                   Like a careless Prodigal;
                   Telling tales about the sun
                   When we’ve little warmth, or none.”

And one of the earliest parasitic fungi in spring is an _Æcidium_ which
flourishes on its glossy leaves. So common is _Æcidium ranunculacearum_
on this species of _Ranunculus_, that it can scarcely have escaped the
eye of any one who has taken the trouble to examine the plant. It
appears in patches on the under surface of the leaves or on their
petioles, in the latter case swelling and distorting them. Sometimes
these patches are nearly circular, at others of very irregular form, and
varying in size from less than one-twelfth of an inch to half an inch in
diameter. It is found on several species of _Ranunculus_, as _R. acris_,
_bulbosus_, and _repens_, but most commonly on _R. ficaria_. The leaf is
thickened at the spot occupied by the parasite, and generally without
indication on the opposite surface. Sometimes one spot, at others
several, occur on the same leaf. The peridia are densely crowded
together, often arranged in a circinate manner, _i.e._, like a
watch-spring, or the young frond of a fern. The spores are orange, but
slightly varying in tint on different species of _Ranunculus_ (Plate II.
figs. 12-14). One of the smaller clusters, when collected before the
spores are dispersed, or the teeth of the peridium discoloured, mounted
dry as an opaque object, makes a very excellent slide for an inch or
half-inch objective; and the same may be said of many others of the same
genus.

Less common than the foregoing is the species of _Æcidium_ which attacks
the violet. The sweetest of flowers as well as the earliest, in despite
both of its odour and its humility, becomes a victim to one or more of
the ubiquitous race of fungi. Thickened spots at first appear on the
leaves; the petioles, or flower stem, or even the calyx, become swollen
and distorted; and at length the cluster-cup breaks through. The spots
on the leaves upon which the peridia are scattered are yellowish,
generally larger than the clusters on the pilewort, and seldom with more
than one spot on each leaf. The peridia, or cups, are irregularly
distributed over the spots, not crowded together as in the last species;
and the teeth are large, white, and distinct. The spores are at first
orange, but at length become brownish. This species may be found in
spring, as late as June, most commonly on the dog-violet, but also on
other species of _Viola_.

It is not a very desirable occupation to search a bed of nettles, and
turn over the individual leaves to look for minute fungi. A very pretty
_Æcidium_ is nevertheless far from uncommon in such a habitat.
Fortunately it occurs very often on the petioles of the leaves and on
the stem, distorting them very much; and in such situations flourishing,
apparently, more vigorously than when occupying the under surface of the
leaves (Plate I. fig. 10). In the latter situation the clusters of
peridia are small, seldom exceeding a dozen in a spot, but several spots
may be found on the same leaf. On the stem they are clustered around for
upwards of an inch in length, and their bright orange colour in such a
situation renders them very conspicuous objects. The peridia are always
closely packed together upon a thickened base, and offer but slight
variations from the forms already enumerated, save that they widen
slightly at the mouth, so as to become nearly campanulate. The spores
are orange, and very profuse.

During the past summer we noticed, for the first time, a very pretty
little species of cluster-cup (_Æcidium_) on the wood sanicle (_Sanicula
Europæa_) in Darenth wood. It was far from uncommon, and we believe it
to be specifically distinct from its nearest ally, found on the earthnut
leaves, and those of some other umbelliferous plants. The little cups
are in small clusters of four or five together, on the under surface and
on the petioles; they are small, but the teeth are relatively large,
white, and distinct. The spores are of a pallid, yellowish colour, and
not so profuse as in the last species. A darker spot on the upper
surface of the leaf generally indicates their presence. This species was
found many years ago by Carmichael at Appin, and called by him _Æcidium
saniculæ_; but we find no notice of its occurrence since, though it
seems to be far from uncommon at Darenth, and probably elsewhere, should
the sanicle be common also.

Recently we found the bedstraw cluster-cup (_Æcidium galii_) on the
great hedge bedstraw (_Galium mollugo_), and as it has not been figured
before, we have included it amongst our illustrations (Plate II. figs.
15-17). Though very insignificant when occurring on the small leaves of
the yellow bedstraw (_Galium verum_), it is a prominent object on the
above-named species.

We received, for the first time, in July, 1864, from Mr. Gatty, student
at Winchester, a portion of a plant of _Thesium humifusum_ (which is by
no means common in Britain), covered with beautiful cluster-cups of a
species never before recorded as occurring in this country (Plate III.
figs. 50, 51) named _Æcidium Thesii_, but which is far from uncommon on
the Continent. It occurred in this instance on the Downs, in the
vicinity of Winchester.

It is unnecessary here to refer to other allied species of _Æcidium_,
except one to be presently noticed, since we have, at the end of the
volume, enumerated and given descriptions of all the species hitherto
found in Britain. Suffice it to say that the Buckthorn cluster-cups on
the alder buckthorn (_Rhamnus frangula_), is usually very common in the
Highgate and Hornsey woods, and on the common buckthorn (_Rhamnus
catharticus_) in the neighbourhood of Dartford, in Kent. That on the
honeysuckle we have found but very rarely. On the gooseberry and
red-currant leaves, commonly in some years and rarely in others; whilst
a few of those described we have never collected. The species on
different composite plants is subject to great variation, and on most
may be found in the autumn; one variety only, on the leaves of _Lapsana
communis_, we have met with in the spring.

Very few years ago farmers generally believed that the cluster-cups of
the berberry (_Berberis vulgaris_), were productive of mildew in corn
grown near them; this opinion even received the support of Sir J. Banks,
but no fungi can be much more distinct than those found on corn crops
and this species on the leaves of the berberry. In this instance the
cups are much elongated, and cylindrical, the clusters vary much in
size, and the spots on the upper surface of the leaf are reddish,
bright, and distinct. The teeth are white and brittle, and the orange
spores copious (Plate I. figs. 7-9).

There are scarcely any of the epiphyllous fungi forming equally handsome
or interesting objects for low powers of the microscope, than the genus
to which attention has just been directed; and they possess the
advantage of being readily found, for that locality must be poor indeed
which cannot furnish six species during the year. We have found half of
the number of described species within little more than walking distance
of the metropolis, within a period of little more than three months, and
should be glad to hear of the occurrence of any of the rest.

We have three species of fungi very similar in many respects to the
foregoing, but differing in others to such an extent as to justify their
association under a different genus and name. The hawthorn is a bush
familiar to all who love the “merry month of May,” but it may be that
its parasite has been unnoticed by thousands. If, for the future, our
readers will bear this subject in their minds when they stand beneath a
hawthorn hedge, they may become acquainted with clusters of singular
brown pustules on the leaves, petioles, and fruit well worthy of more
minute examination (Plate II. fig. 22). They scarcely claim the name of
cups, and their lacerated and fringed margins rather resemble the pappus
crowning the fruits of some composite plants than the cups of _Æcidium_.
The peridia are very long, and split down throughout their length into
thread-like filaments of attached cells; these gradually fall away and
break up into their component parts till but short portions remain
attached to the base of the peridia. These cells are elongated and
marked on the surface with waved lines, forming in themselves pretty
objects for a high power of the microscope (Plate II. figs. 23, 24). If
the teeth of _Æcidium_ resemble the peristome of some mosses, such as
_Splachnum_; the threads of this species of _Rœstelia_, except in not
being twisted, somewhat resemble the peristomes of other mosses of the
genus _Tortula_. The spores in this species are less conspicuous, being
of a light brown, and the whole plant, from its modest hue, may be
readily passed over without attracting attention unless occurring in
abundance.

The leaves of pear-trees afford a second species of this genus
sufficiently distinct to commend it to our notice. Sometimes it is very
common, at others but few examples are to be met with. The clusters
occur on the under surface, and consist of half-a-dozen or less of large
peridia, pointed at the apex and swelling in the middle so as to become
urn-shaped (Plate II. figs. 20, 21). These vessels or thecæ split into
numerous threads or laciniæ, which remain united together at the apex.
Like the species already noticed, this is brown and inconspicuous except
on account of its size, for it is the largest of all that we have had
occasion to notice.

The third species occurs on the under surface of the leaves of the
mountain-ash. The peridia are clustered on a rusty orange-coloured spot
which is visible on the upper surface (Plate II. figs. 18, 19). They are
long and cylindrical, with an evident tendency to curvature; the mouth
is serrated, but not split up into threads, as in the species found on
the hawthorn. There will often be found instead of well-developed
peridia, what at one time were regarded as abortive peridia, forming a
thickened orange or rust-coloured spot, studded with minute elevated
points. These spots are clusters of spermogones, which organs are
described in detail in our second chapter. The clusters and spores are
of a brighter reddish-brown than in either of the other species. All are
remarkably distinct, and perhaps the most curious and interesting of any
that we have passed in review. To botanists, the species found on the
hawthorn is known as _Rœstelia lacerata_, that on pear-leaves as
_Rœstelia cancellata_, and the one on the leaves of the mountain-ash as
_Rœstelia cornuta_.

Dr. Withering observed the spore-spots on the leaves of the
mountain-ash, but was evidently puzzled to account for them. He writes
(in his Arrangement of British Plants), “The spots on the leaves of
_Sorbus aucuparia_ consist of minute globules intermixed with wool-like
fibres. On examining many of them in different states, I at length found
a small maggot in some of the younger spots, so that the globules are
probably its excrement, and the fibres, the woody fibres of the plant
unfit for its food.” We now-a-days smile at such simple and singular
conjectures. It affords evidence of the manner in which the speculations
of one generation become follies in the next.

Only two species of cluster-cups are described in Withering’s Flora
under the genus _Lycoperdon_: one of these is now called _Æcidium
compositarum_, and is found on various composite plants; the other
includes the species found on the wood-anemone and that on the
moschatel, and also probably a species of _Puccinia_ on the wood-betony.

To render this chapter more complete, though of less importance to the
microscopist, we may allude to the other two genera comprised within
this order. _Peridermium_ is the name of one genus which contains two
British species found on the leaves and young shoots of coniferous
trees. In this genus the peridium bursts irregularly, and does not form
cups, or horns, or fringed vessels. The most common species is found on
the needle-shaped leaves of the Scotch fir (Plate II. fig. 27), and also
on the young twigs, in the latter instance larger and more prominent
than in the former. The elongated peridia burst irregularly at their
apices without forming teeth (fig. 28).

In the genus _Endophyllum_, as its name implies, the peridium is
imbedded within the substance of the succulent leaves. The only species
we possess is found rarely upon the common house-leek.

We have derived much pleasure in viewing the astonishment and delight
exhibited by friends to whom we have personally communicated specimens
of the little fungi we have enumerated for examination under the
microscope; and we recommend with confidence this group of parasitic
plants, unfortunately so little known, as well worthy of the attention
of all who are interested in the minute aspects of nature, and who can
recognize the hand—

             “That sets a sun amidst the firmament,
              Or moulds a dew-drop, and lights up its gem.”


------------------------------------------------------------------------



                              CHAPTER II.

                             _SPERMOGONES._


IN addition to their spore-bearing spots, lichens have for some time
been known to possess other organs, termed _spermogones_, which are
probably concerned more or less in the reproductive process. The first
intimation of the existence of similar bodies in the entophytal fungi
originated with M. Unger in 1833, but it was left to Dr. de Bary and the
Messrs. Tulasne, twenty years later, to examine and determine
satisfactorily the nature and value of the spermogones of the Uredines.
It was at first believed that the smaller pustules—which sometimes
precede, and sometimes accompany, the cluster-cups and some other allied
fungi—were distinct species developed simultaneously therewith, or
members of a new genus, which, under the name of _Æcidiolum
exanthematum_, found a place in the mycologic system.

Without staying to trace the stages through which the elucidation of
their true nature proceeded, it will suffice for our purpose to tell
what is now known of these secondary organs; to accomplish which we must
stand greatly indebted to the independent researches of Messrs. de Bary
and Tulasne. It has been demonstrated that both these bodies, namely,
the primary organs or cluster-cups, and the secondary organs or
spermogones, are developed from the same mycelium; but the value of the
latter is still undetermined. If they possess any fecundative power, the
process has not been traced; or if they are in themselves reproductive,
they have not at present been seen to germinate. Their uses, therefore,
in the economy of the parasitic plant of which they are now known to
form a part is still a mystery, and they remain valueless in the
determination of genera and species. Any speculation which might regard
them as male organs would be premature, and without support in fact.
Hitherto only some species of the genera described in the foregoing
chapter, and others belonging to genera not hitherto named, have been
ascertained to possess spermogones. Of the former are the _Rœsteliæ_,
some species of _Æcidium_, as those of _Euphorbia_, &c., and
_Peridermium Pini_.

These spermogones are of a very simple structure—very delicate, indeed;
so much so, that they will scarcely bear preparation for demonstration.
De Bary states that they originate from plain, delicate, inarticulate
threads, about half the thickness of the mycelium (the root-like
branching fibres which form the fundamental stratum of fungoid growths),
which are developed in large quantities, and closely packed together.
These threads are compacted together so as to form an outer enveloping
integument or peridium, which is either globular or hemispherical (or in
some instances elongated), more or less immersed, and at length opening
at the apex (fig. 153) by a regularly formed minute ostiolum. The inner
wall of the peridium is covered with a thick forest of simple filaments
standing on end. From the summit of these filaments or sterigmata, the
spermatia are borne. These are either isolated or associated together in
strings or chaplets, are exceedingly minute, of an ovoid or oblong
shape, and are produced in such numbers as to fill the cavity of the
spermogone. Besides these, a viscid fluid is secreted, in which the
spermatia are immersed, and which is expelled with them from the orifice
of the peridium. According to the density of this fluid, or the
hygrometric state of the atmosphere, it appears sometimes in drops, and
sometimes oozing out in threads or cirrhi from the spermogones. To
compare minute things with gigantic, as a recent author has observed, it
resembles the lava issuing from the crater of a volcano. The colour of
this spermatiferous matter is commonly orange, but in some instances
brown, though not constantly of the same colour as the spores produced
from the same mycelium. This gelatinous substance is dissolved away from
the granular bodies which are immersed in it, by adding a little water
upon the slide on which the mass is placed for examination. The
granules, or spermatia, then exhibit those peculiar movements which have
been observed in the similar bodies in lichens, and fitly described as
“a sort of oscillating motion, as of a body attached at one extremity.”
The cause of this motion is at present uncertain, vibratile ciliæ, to
which similar movements are referred, being altogether absent; but
probably, as De Bary believes, the cause may be found in the influence
of exosmose.

The largest spermatia yet examined (those of _Peridermium Pini_) have a
length equal to 1/2500 of an inch, but their width seldom exceeds
1/100000 of an inch, whilst in others their length does not exceed the
width of those just named.

Messrs. Tulasne affirm that all these corpuscles, as well as the
mucilaginous fluid, evolve an appreciable odour, resembling that of the
pollen of the willow. M. Léveillé compares the odour to that of orange
flowers, and M. de Bary to that of the evening primrose.


                              SPERMOGONES

[Illustration:

  FIG. 1.—_Æcidium grossulariæ_. _c._ Cluster-cups. _s._ Spermogones.
]

[Illustration:

  FIG. 2.—Section of ripe spermogones of _Æcidium Euphorbiæ_. _s._
    Spermatia. _a._ Sterigmatæ bearing spermatia (_De Bary_).
]


The spermogones do not always appear like pustules on the surface of the
leaves, for sometimes their presence is only indicated by minute
depressed punctures which are scarcely visible; generally, however, they
may be recognized by an obtuse, or otherwise a pointed, protuberance
that surmounts them. The margin of the orifice is sometimes furnished
with short hairs, but is more frequently ornamented with a pencil of
long hairs, which are stiff and erect, and of the colour of the enclosed
spermatia.

In many of the species of _Æcidium_ the cups are disposed in a more or
less regular circle, the centre of which is occupied by a group of
spermogones; at the same time, the corresponding spot on the opposite
surface of the leaf will frequently be found also occupied by other
spermogones—in some instances in greater number than on the same surface
of the leaf on which the cups are seated. This is the case in the
_Æcidium_ which is found upon the leaves of the coltsfoot, and that of
the honeysuckle.

Very bright orange-coloured spots may be observed in autumn (we have
encountered them often in August and September) upon the leaves of pear
trees, and which are covered with little tubercles, at first of the same
colour, but ultimately becoming brown. These pustules are so many
spermogones belonging to _Rœstelia cancellata_, a kind of cluster-cup
found in the same localities. These spots have long since been noticed,
and regarded as connected with the _Rœstelia_, but in what manner has
until recently been unknown. The Rev. M. J. Berkeley noticed them in the
English Flora in 1836, or at least the granulations on the upper
surfaces of the leaves bearing _R. cancellata_, _R. cornuta_, and _R.
lacerata_, and called them abortive pseudoperidia. Before this (in 1804)
they had been observed by Rebentisch. An examination of one of these
spots under a low power of the microscope, and afterwards a section of
one or more of the pustules, cut with a sharp razor, and viewed with a
higher power, will give an idea of the nature of the bodies we are
attempting to describe. During the past summer we have noticed very
similar orange spots on leaves of the berberry containing spermogones on
both surfaces, and these appeared before any cups had been found on that
plant. In this instance no cups were produced from the spots on the
leaves examined, and which were carefully noticed at intervals until
they withered and fell.

In some instances, as in _Rœstelia cornuta_, which is found on the
leaves of the mountain-ash, the cups are produced on the lower, but the
spermogones almost exclusively on the upper surface.

The spermogones of _Peridermium Pini_ are white, few in number, and are
developed, not only in the spring, but sometimes reappear in the autumn
upon the same leaves that produced them at the commencement of the year.

In such instances as those of the _Æcidium_ of the spurge, and also the
goatsbeard, in which the cluster-cups are arranged in no appreciable
order, the spermogones are scattered amongst them, and even in some
instances appear on different leaves. The spermogones are common on the
wood spurge in spring, scattered over both surfaces of the leaves before
the cluster-cups make their appearance, and gradually these latter are
developed amongst them, commencing from the apex of the leaves and
proceeding in the order of their development towards the base. In this
instance the spermogones are bright yellow, as are afterwards the cups
and spores of the _Æcidium_. In most instances the appearance of the
spermogones precedes that of the sporiferous organs, but the latter
follow sufficiently speedy for perfect development before the decadence
of the spermogones takes place.

After the expulsion of the spermatia and the fluid which accompanies
them, the whole mass dries up; and where many spermogones have been
clustered together in the same spot a brown homogeneous crust is formed
upon the epidermis; where they are produced singly, a brownish
incrustation is visible about the mouth of each spermogone.

Re-agents applied to the spermogones whilst in full vitality indicate
the presence of a considerable amount of a protein substance, which,
with sugar and sulphuric acid, produces a deep purple red colour.

From what we have already stated of the method of occurrence of these
organs, the following is the only order, apparently, preserved in their
development, although no definite rules can at present be affirmed. The
spore spots of cluster-cups are generally found upon the under surfaces
of the leaves on which they are produced, and the spermogones are most
numerous on the upper. When both the cluster-cups and the spermogones
appear in the same group on the same surface, the spermogones commonly
occupy the centre, and the cups are arranged in a circular manner about
them. In other, and fewer instances, both organs stand together
indiscriminately upon the same surface.

The spermogones are also developed centrifugally, at least so far as at
present observed, for when they are produced in a cluster the central
one first opens and discharges its contents, and thus the development
proceeds outwards from the centre to the circumference. When the
spermogones are scattered, as in those of _Euphorbia_, they are first
observed at the apex of the leaf, whence they are developed in
succession towards the base. The latter should be sought for on the
young plants of the wood spurge in March or April, at which time we have
found them abundant at Darenth wood, near Dartford.

It must not be concluded, from the fact that we have not yet adverted to
spermogones in connection with other fungi, that they are peculiar to
the _Æcidiacei_. Such is by no means the case. As we have hereafter
described other genera and species in which spermogones occur, it would
be out of place to enter upon further details here. Let it suffice
therefore that we state that they have been found in members of the
genera, _Aregma_, _Triphragmium_, _Puccinia_, _Lecythea_, _Trichobasis_,
and _Uredo_, but they have been found much more generally in _Rœstelia_
and _Æcidium_ than in any other genus.

As comparatively little is yet known of these bodies, a fair field is
open to the enterprising microscopist, with time at his disposal, and a
good store of perseverance, to win for himself renown in the discovery
of fresh facts, and the elucidation of some of the mysteries which yet
enshroud these interesting organisms. From the foregoing pages he will
learn the direction in which his researches should tend, and he may be
assured that every new fact is of importance when carefully ascertained.


[Illustration:

  Plate II.
  W. West imp.
]


------------------------------------------------------------------------



                              CHAPTER III.

                             _DI-MORPHISM._


BEFORE entering further and more fully upon the subject of this volume,
it may be advisable to attempt an explanation of a phenomenon of no
uncommon occurrence in many groups of Fungi, and which is termed
_di-morphism_.

In the Uredines, or uredo-like fungi, as well as other of the
_Coniomycetes_ (in which the spores are the principal feature), the same
fungus appears under two or more distinct forms, not necessarily mere
differences of age, but so distinct that they have been regarded (and
some are so still) as different species belonging to different genera,
often far removed from each other, and bearing different names. One
plant, for instance, sprinkled over the under surface of a rose-leaf,
like turmeric powder, has its mycelium, or root-like threads,
penetrating the tissue, whilst bearing above its spherical
golden-coloured spores. Its vegetative system is complete, and,
apparently, its reproductive also; hence it seems to claim recognition
as a perfect plant, and under the name of _Uredo Rosæ_ was so
recognized, until microscopical investigation determined otherwise. Thus
it has been discovered that certain dark brown spots which appear later
in the season are produced upon the same mycelium, and are indeed
aggregations of more perfect and complex fruits of the same plant.
Before this point was satisfactorily decided, the brown spores, which
are borne on long stalks, and are themselves septate or divided
(apparently or really) by transverse partitions into a complex fruit,
received the name of _Puccinia Rosæ_. At this period, _Uredo Rosæ_ and
_Puccinia Rosæ_, or the yellow fungus and the dark brown fungus, were
believed to be distinct and different plants; now, on the contrary, they
are believed to be different forms of fruit produced by the same plant;
_i.e._, an instance of di-morphism. _Aregma mucronatum_, Fr., is the
present scientific name of what is regarded as the perfect fungus,
whilst the uredo-form either bears the name of _Lecythea Rosæ_, Lev., or
by some mycologists is rejected altogether as a spurious species.

During the summer it is not uncommon to find the leaves of some grasses,
of the hop, of roses, and many other plants, covered with a kind of
white mould, which appears under the microscope as a multitude of small
transparent colourless cellules, generally attached to each other in a
moniliform or beaded manner. These moulds were long known under the
generic name of _Oidium_, to which genus the vine disease was also
referred. More minute investigation and more careful examination proved
that these moulds were not in themselves perfect plants, but merely
conditions of other fungi of a higher order, little differing it is true
in external appearance to the naked eye, but offering material
differences in structure under the microscope. Upon the white mould-like
threads, spherical bodies are produced in the autumn, containing little
sacs or asci filled with spores; and in this condition the plants are
arranged under the genus _Erysiphe_, whilst the species of _Oidium_
which represented their imperfect condition, are excluded from the
system. Here, again, we have examples of _di-morphism_.

In the Journal of the Microscopical Society, Mr. F. Currey has detailed
several instances of di-morphism which have fallen within his
experience. In one instance he has shown that a small simple spored
fungus, termed _Cryptosporium Neesii_, Ca., is only a state or condition
of a fungus with compound fruit, belonging to the _Sphœria_ section of
ascigerous fungi, called _Valsa suffusa_, Fr. Both plants are exactly
alike externally, but the perithecium, or flask-like receptacle
containing the fructification, in one instance only holds naked spores,
and in the other the spores are contained in little elongated vesicular
bags or asci, which are packed within the perithecium.

Whilst writing this, one of the most wonderful books in a book-producing
age lies beside us; it is the second volume of a work on fungi, by the
brothers Tulasne; and this, as well as its predecessor, is devoted to
this very subject of a multiplicity of form in the fructification of
these plants. Illustrated by the most exquisite of engravings which art
has ever produced, it also unfolds many a page in the history of these
organisms, for which mycologists were not altogether unprepared. In
noticing this work, one of our most eminent authors on mycological
subjects quotes as an example _Dothidia ribis_, Fr., one of our most
common fungi, which occurs in the form of little black shields on dead
twigs of currants and goose-berries. Here we have, he says, naked spores
(_conidia_) growing on the external cells of the stroma; we have naked
spores of a second kind (_stylospores_) produced in distinct cysts
(_pycnides_); we have minute bodies of a third kind (_spermatia_)
produced again in distinct cysts, resembling very closely similar bodies
in lichens; and we have a third kind of cysts, containing the usual
sporidia in sausage-shaped hyaline sacs (_asci_). Even here, however, we
have not done with marvels; for if the stylospores are placed in water,
they produce in the course of twenty-four hours conidia of a second
order, exactly analogous to those which arise on the germination of the
spores of the rusts and mildews which affect our cereals and other
plants.

Further reference is also made to three species of moulds, which M.
Tulasne has shown to be only varied forms of the mycelium of a species
of _Sphœria_ common to various plants; these moulds having been hitherto
regarded as fungi perfect in themselves.

In the Uredines, to which much of this volume is devoted, the genera
known as _Lecythea_ and _Trichobasis_ are by some mycologists excluded
altogether, as containing only species which are mere forms of more
highly-developed uredines, such as _Puccinia_, _Aregma_, and others. On
the other hand, they are retained by those who possess a lingering doubt
whether both forms may not be distinct, though developed from the same
pustule. As the two forms are distinct in appearance, it will better
answer our present purpose to treat them separately, notwithstanding the
belief that, in a scientific point of view, the evidence is all in
favour of their union.

In fungi of this kind the mycelium, or delicate root-like threads,
consists of thin filaments, which are spread through all parts of the
plant occupied by the parasite, traversing the intercellular passages,
but rarely perforating and entering the cells. This compacted and
interwoven mycelium forms a kind of cushion beneath each pustule, on
which the fruits of the parasite rest. By the increase of this cushion
and the swelling of the fruit, the epidermis which covers them is
distended, and ultimately ruptured, so that, when ripened, the spores
escape. It must be remembered that the fruit is of from two to four
kinds. Small bodies, called _spermatia_, which are derived from the
spermogones, and which have not yet been known to germinate;
_Stylospores_, produced either singly, or in bead-like, or moniliform,
strings, and which either precede or are associated with the true
spores; _Spores_, sometimes simple, but often complex; and _Sporidia_,
or secondary sporules, which are produced on the germinating threads of
the true spores.

The various genera of these endophytes owe their distinctions to the
form, or mode of development of their true spores. In one instance these
spores are united in pairs, or divided by a septum, so that they are
two-celled: these are named _Puccinia_. In another instance the spores
are one-celled, and at first borne upon a stalk or peduncle, from which
they are detached in ripening: such are called _Trichobasis_. It is
unnecessary here to indicate all the variations to illustrate the fact
that the generic distinctions are based upon the characters of the true
spores. How unsatisfactory such a mode will appear, when subjected to
experience day by day, a botanist would suspect. In the same pustule,
resting upon the same cushion of mycelium, the spores of an _Aregma_
will be found with those of a _Lecythea_, and those of a _Puccinia_ with
_Trichobasis_. More than this has even been affirmed. The alternation of
generations, known to students in the animal world, is here repeated in
the vegetable. Dr. de Bary declares that certain data appear to indicate
that _Æcidium_ constitutes not a genus by itself, but are organs in the
development of some other germs and species, possessing its spermogonia,
its _Æcidium_; its _Uredo_, and its spores, properly speaking; whilst in
others the _Uredo_-form the _Puccinia_-form, and the _Æcidium_-form may
alternate. It is not our intention to enter deeply upon the discussion
of this subject, of so little interest to the beginner, and so out of
place in an introduction to the study. That forms and conditions are
multifarious, and that an entire revision of the classification is
inevitable, are facts which do not require many words to establish.
Already it is to be feared that in this brief chapter we have said too
much, and must recommend its perusal again, when the names and
characters of the genera alluded to have been rendered more familiar.

It could scarcely have been permitted that the student should go far
without being cautioned that there is such a thing as di-morphism in
microscopic fungi; and the explanation of such a phenomenon must
presuppose a certain amount of knowledge which, thus far, the reader
could not have acquired. Hence an anomaly, to escape from which an
ultimate return to the subject will be necessary.

In a recent account of Dr. de Bary’s experiments,[3] an interesting
history is given of the development of a rust-like fungus, which is
common on many plants of the pea and bean tribe. As it may serve to
illustrate some of the preceding, as well as subsequent, remarks on
development, an abstract shall close this chapter.

Footnote 3:

  De Bary—“Annales des Sciences Naturelles,” ser. 4, vol. xx.

The spores of this species (_Uromyces appendiculatus_) are oboval cells,
terminated by a rounded point, provided with a deep brown, smooth,
_epispore_, or outer coating, and a distinct, but colourless
_endospore_, or inner coating. These enclose a granular matter, which
surrounds what has been termed the nucleus, but which appears to be a
vacuole. At the top of the epispore is a pore which is characteristic of
the genus. The spores are supported on a colourless, or slightly-tinted
pedicel of considerable length (Plate VII. fig. 150). By means of this
pedicel, the spores are attached to the fostering plant, on which they
form pustules or sori of a blackish colour, and variable extent. These
spores are ripened towards the end of summer or beginning of autumn.
During winter they remain in a state of repose, but in the following
spring the faculty of germination developes itself. At this period, when
moistened or placed on a humid soil, they germinate at the end of a few
days. The spore then emits a curved and obtuse tube, which soon ceasing
to elongate itself, gives origin to three or four sporidia, of a
reniform or kidney shape. When cultivated on moistened glass, these
sporidia also emit a short, thin, slender tube, which produce in turn
secondary sporidia. Here vegetation ends in the artificial culture above
indicated.

When the sporidia are sown upon the epidermis of a favourable plant, the
germ-tube being emitted, penetrates the wall of any approximate cellule,
swells and increases into a cylindrical tube equal in thickness to the
original sporidia, and therefore four or five times the diameter of the
germ-tube before it entered the cellule. The contents of the sporidia
and external portion of its germ-tube pass into the portion within the
cellule, and then these external portions perish, and all evidence of
the entry is obliterated, except a very minute point at which the tube
remains attached to the inner surface of the wall of the cellule. The
enclosed tube soon elongates, divides, and becomes branched. These
branches perforate the inner walls of the epidermis, and pass into the
intercellular spaces of the parenchyma to become mycelium. This takes
place within 24 hours. A few days afterwards the mycelium is spread
through the parenchyma. At length the surface of the same spots which
had been sown in the first instance with the sporidia, become of a
whitish tint, rapidly increasing and intensifying. Three days after,
little protuberances appear on the surface of the white spots. These are
of an orange colour, and many of them are surmounted by a little drop of
mucilaginous fluid. These are _spermogones_. Their number daily
increases, and a little time after appear numerous large globular
protuberances intermingled with them. These soon rupture the epidermis,
and take the orange colour and cylindrical form of cluster-cups
(_Æcidium_). At length the summit of the peridia opens to allow the
escape of the _stylospores_. It is easy to assure oneself that the
spermogones and cluster-cups proceed from the mycelium of the sporidia
which had been sown. During several days the length and number of the
peridia of the _Æcidium_ continue to increase. One month after sowing,
brownish or blackish points make their appearance upon the whitish
spots, around, or intermingled with the cluster-cups. These increase
rapidly in number and magnitude. Examined by the microscope, they
present the ordinary fructification of _Uromyces_, mingled with
stylospores. Thus the mycelium of the cluster-cups engenders at the end
of its vegetation fruits equal in all points to those from whence they
are in the first instance derived.

The stylospores of the cluster-cups possess the irregular, globular form
and structure of their congeners. They are filled with orange granular
matter, and provided with a colourless, finely-punctated epispore. When
these stylospores are sown on the moistened epidermis of a favourable
plant, the germ-tube at first creeps along the surface, but as soon as
its extremities find a stomate, it enters it and elongates itself in the
air-cavity below the orifice, receives the contents of the original
stylospore and exposed portion of its tube, then separates itself from
those parts, which become dispersed. The active part increases and
ramifies, and produces a mycelium which spreads through the
intercellular passages of the parenchyma. At the end of from six to
eight days, the whitish spots appear on the surface of the fostering
plant, and indicate that the fructification of the parasite is about to
commence. The epidermis is elevated and broken, and little brown
pustules appear through the openings. These are the _stylospores_ of
_Uredo_, which are produced in immense quantities, and soon cover the
pustules with a deep brown dust. Later, the formation of the stylospores
is arrested, and the true germinating spores appear in the same
pustules.

The stylospores of _Uredo_ are borne singly at the top of short
filaments. On arriving at maturity they detach themselves. They are of a
globular form, with a reddish-brown epispore, provided with little
pointed prominences, and three pores at equal distances. After maturity
they germinate in precisely the same manner as the stylospores of the
cluster-cups. They enter only through the stomata of the epidermis. The
pulvinules are identical with those which the stylospores of _Æcidium_
originate, and they also produce true spores at the end of their
vegetation. No other fruit arises from them. These organs, therefore,
always reproduce the same form to which they owe their origin. The
result of these investigations shows that the bean rust (_Uromyces
appendiculatus_), besides spermogones, possesses four sorts of
reproductive organs, which all serve to propagate the species, but that
one alone of them produces it in a form always identical, whilst the
others present well-marked alternations of generation. Hence it is
concluded that there are,

I. _Spores_ which produce in germinating the promycelium, and

II. _Sporidia._—These give place to a mycelium, which bears afterwards—

III. _Æcidium._—Particular organs which engender stylospores, and which
produce—

IV. _Uredo_, the second form of the stylospores, and later spores (No.
I.), which are always associated with _Uredo_ in the same pustule. The
spores and stylospores of _Uredo_ come also upon the old mycelium, which
has previously produced _Æcidium_. The _Uredo_ stylospores always
produce _Uredo_, and true spores.


------------------------------------------------------------------------



                              CHAPTER IV.

                          _MILDEW AND BRAND._


DR. WITHERING’S “Arrangement of British Plants” in 1818 reached its
sixth edition. This is less than half a century ago, and yet the whole
number of species of Fungi described in that edition was only 564, of
which three hundred were included under the old genus _Agaricus_. Less
than eighty of the more minute species of Fungi, but few of which
deserve the name of microscopic, were supposed to contain all then known
of these wonderful organisms. Since that period, microscopes have become
very different instruments, and one result has been the increase of
Withering’s 564 species of British Fungi to the 2,479 enumerated in the
“Index Fungorum Britannicorum.” By far the greater number of species
thus added depend for their specific, and often generic characters, upon
microscopical examination. The proportion which the cryptogamic section
bears to the phanerogamic in our local Floras before 1818, now almost
involuntarily causes a smile. Even such authors as were supposed to pay
the greatest possible respect to the lower orders of plants could never
present an equal number of pages devoted to them, as to the higher
orders. Relhan, for instance, only occupies one-fifth of his “Flora
Cantabrigiensis,” and Hudson one-fourth of his “Flora Anglica,” with the
Cryptogamia. At the present time, it will be seen that, with a liberal
allowance for “hair-splitting,” the number of British species of
flowering plants scarcely exceeds three-fourths of the number of Fungi
alone, not to mention ferns, mosses, algæ and lichens, and yet we have
no “Flora” which contains them, and but a minority of our botanists know
anything about them. If we need excuse for directing attention to some
of the most interesting of these plants, let the above remarks suffice
in lieu of formal apology.

“Mildew” is just one of those loose terms which represent no definite
idea, or a very different one to different individuals. Talk of _mildew_
to a farmer, and instantly he scampers mentally over his fields of
standing corn in search of the brown lines or irregular spots which
indicate the unwelcome presence of _Puccinia graminis_, known to him,
and to generations of farmers before him, as “mildew.” Try to convince a
Norfolk farmer that anything else is “mildew,” and he will consider you
insane for your pains. Speak of _mildew_ in your own domestic circle,
and inquire of wives, or daughters, or servants, what it means, and
without hesitation another, and even more minute species of fungus,
which attacks damp linen, will be indicated as the true mildew, to the
exclusion of all others; and with equal claims to antiquity. Go to
Farnham, or any other hop-growing district, and repeat there your
question,—What is _mildew_?—and there is every probability that you will
be told that it is a kind of mould which attacks the hop plant, but
which differs as much from both the mildew of the farmer and the
laundry-maid as they differ from each other. The vine-grower has his
mildew, the gardener his mildewed onions, the stationer his mildewed
paper from damp cellars, the plasterer his mildewed walls, and in almost
every calling, or sphere in life, wherever a minute fungus commits its
ravages upon stock, crop, or chattels, to that individual owner it
becomes a bug-bear under the name of “mildew.” Reluctantly this vague
term has been employed as a portion of the title to this chapter, but it
must be limited in its application to the “mildew of corn,” known to
botanists as _Puccinia graminis_, and _not_ to include the numerous
other microscopic Fungi to which the name of _mildew_ is often applied.

The origin of this term and its true application may undoubtedly be
traced to _mehl-thau_, “meal dew.” A singular proof of the ignorance
which prevails in regard to all the fungal diseases of corn, may be
found in the fact that at least one of our best etymological
dictionaries states that the _mildew_ in corn is the same as the _ergot_
of the French. Had the writer ever been a farmer, he would have known
the difference; had he ever seen the two, he could scarcely have made
such a mistake. It is barely possible for him ever to have heard the
ergot of grain called by the name of _mildew_.

How long this disease has been known, is an unsolved problem. About the
middle of the last century a tract was published on this subject in
Italy, but this was probably not even the first intimation of its
fungoid character. Before such conclusion had been arrived at, men may
have struggled in the dark, through many generations, to account for a
phenomenon with which they were doubtless familiar in its effects. In
1805, Sir Joseph Banks published his “Short Account,” illustrated by
engravings from the inimitable drawings of Bauer, whereby many in this
country learnt, for the first time, the true nature of _mildew_.


[Illustration:

  Plate III.
  W. West imp.
]


With a view to the clearer understanding of these parasites in the
phases of their development, let us select one, and we cannot do better
than adhere to that of the wheat and other graminaceous plants. A fine
day in May or June dawns upon our preparations for a stroll, far enough
into the country to find a wheat-field. Even now, with the area of the
metropolis constantly widening, and banishing farmers and wheat fields
farther and farther from the sound of Bow-bells, a corn field may be
reached by a good stiff walk from Charing-Cross, or a six-penny ride at
the most, in nearly any direction. Having reached the field, it may be
premised that a walk into it of less than twenty yards will be sure to
reward you with the fungus we are in quest of. Look down at the green
leaves, especially the lower ones, and you will soon find one apparently
grown rusty. The surface seems to be sprinkled with powdered red ochre,
and grown sickly under the operation. Pluck it carefully, and examine it
with a pocket lens. Already the structure of a healthy leaf is familiar
to you, but in the present instance the cuticle is traversed with
numerous longitudinal cracks or fissures, within which, and about their
margins, you discern an orange powder, to which the rusty appearance of
the leaf is due. Further examination reveals also portions in which the
cuticle is distended into yellowish elongated pustules, not yet
ruptured, and which is an earlier stage of the same disease. This is the
“rust” of the agriculturist, the _Trichobasis rubigo-vera_ of botanists,
the first phase of the corn mildew.

To know more of this parasite, we must have recourse to the microscope;
having therefore collected a few leaves for this purpose, we return
homewards to follow up the investigation. We will not stay to detail the
processes of manipulation, since these will not offer any deviation from
the ordinary modes of preparation and examination of delicate vegetable
tissues.

The vegetative system of the “rust,” and similar fungi, consists of a
number of delicate, simple, or branched threads, often intertwining and
anastomosing, or uniting one to the other by means of lateral
branchlets. These threads, termed the mycelium, penetrate the
intercellular spaces, and insinuate themselves in a complete network,
amongst the cells of which the leaf, or other diseased portion of the
plant, is composed. High powers of the microscope, and equally high
powers of patience and perseverance, are necessary to make out this part
of the structure. We may regard the whole mycelium of one pustule, or
spore-spot, as the vegetative system of one fungal plant. At first this
mycelium might have originated in a number of individuals, which
afterwards became confluent and combined into one for the production of
fruit, that is to say, an indefinite number of points in the vicinity of
the future mycelium developed threads; and these, in the process of
growth, interlaced each other, and ultimately, by means of transverse
processes, became united into one vegetative system, in which the
individuality of each of the elementary threads became absorbed, and by
one combined effort a spore-spot, or cluster of fruit, was produced. In
the first instance a number of minute, transparent, colourless cellules
are developed from the mycelium: these enlarge, become filled with an
orange-coloured endochrome, and appear beneath the cuticle of the leaf
as yellowish spots. As a consequence of this increase in bulk, the
cuticle becomes distended in the form of a pustule over the yellow
cellules, and at length, unable longer to withstand the pressure from
beneath, ruptures in irregular, more or less elongated fissures (Plate
VII. fig. 141), and the yellow bodies, now termed _spores_ (whether
correctly so, we do not at present inquire), break from their short
pedicels and escape, to the naked eye presenting the appearance of an
orange or rust-coloured powder. In this stage the spores are globose, or
nearly so, and consist of but one cell Plate VII. figs. 142, 144). It
will afford much instructive amusement to examine one of these ruptured
pustules as an opaque object under a low power, and afterwards the
spores may be viewed with a higher power as a transparent object. The
difference in depth of tint, the nearly colourless and smaller immature
spores, and the tendency in some of the fully matured ones to elongate,
are all facts worthy of notice, as will be seen hereafter.

A month or two later in the season, and we will make another trip to the
cornfield. Rusty leaves, and leaf-sheaths, have become even more common
than before. A little careful examination, and, here and there, we shall
find a leaf or two with decidedly brown pustules intermixed with the
rusty ones, or, as we have observed several times during the past
autumn, the pustules towards the base of the leaf orange, and those
towards the apex reddish-brown. If we remove from the browner spots a
little of the powder, by means of a sharp-pointed knife, and place it in
a drop of water or alcohol on a glass slide, and after covering with a
square of thin glass, submit it to examination under a quarter-inch
objective, a different series of forms will be observed. There will
still be a proportion of subglobose, one-celled, yellow spores; but the
majority will be elongated, most with pedicels or stalks, if they have
been carefully removed from the leaf, and either decidedly two-celled,
or with an evident tendency to become so. The two cells are separated by
a partition or dissepiment, which divides the original cell transversely
into an upper and lower cell, with an external constriction in the plane
of the dissepiment (Plate IV. fig. 59). These bilocular or two-celled
spores are those of the “corn mildew” (_Puccinia graminis_), which may
be produced in the same pustules, and from the same mycelium, as the
“corn rust,” but which some mycologists consider to be a distinct
fungus, others only a modification or stage of the same fungus. After an
examination of the different forms in the allied genera to which these
chapters are devoted, we shall be able with less of explanation and
circumlocution to canvass these two conflicting opinions.

Let us proceed, for the third and last time, to our cornfield, when the
corn is nearly or fully ripe, or let us look over any bundle of straw,
and we shall find blackish spots, from the size of a pin’s head to an
inch in length, mostly on the sheaths of the leaves, often on the culm
itself. This is the fully developed _mildew_, and when once seen is not
likely afterwards to be confounded with any other parasite on straw
(fig. 57). The drawings of Bauer have already been alluded to. Bauer was
botanical draughtsman to George III., and his exquisite drawings, both
of the germination of wheat and the fungi which infest it, are marvels
of artistic skill. A reduced figure from part of one of his drawings is
given (Plate IV. fig. 58), exhibiting a tuft of the bilocular spores of
_Puccinia graminis_ bursting through a piece of wheat straw. These
closely-packed tufts or masses of spores, when examined with a common
lens, seem, at first, to resemble the minute sorus of some species of
fern; but when seen with higher powers, the apparent resemblance gives
place to something very different. The tufts consist of multitudes of
stalked bodies, termed spores, which are constricted in the middle and
narrowed towards either extremity. The partition, or septum, thrown
across the spore at the constriction, separates it into two portions,
each of which consists of a cell-wall enclosing an inner vesicle filled
with the endochrome (fig. 59) or granular contents, in which a nucleus
may often be made out. This species of _Puccinia_ is very common on all
the cereals cultivated in this country, and on many of the grasses. A
variety found on the reed was at one time considered a distinct species;
but the difference does not seem sufficient to warrant a separation.
However near some other of the recognized species may seem to
approximate in the form of the spores, a very embryo botanist will not
fail to observe the distinctive features in the spores of the corn
mildew, and speedily recognize them amongst a host of others; subject,
as they may be, to slight deviations in form, resulting either from
external pressure, checks in development, or other accidental
circumstances, or the variations of age.

There is no doubt in the minds of agriculturists, botanists, _savans_,
or farm-labourers, that the mildew is very injurious to the corn crop.
Different opinions may exist as to how the plants become inoculated, or
how infection may be prevented or cured. Some have professed to believe
that the spores, such as we have seen produced in clusters on wheat
straw, enter by the stomata, or pores, of the growing plant, “and at the
bottom of the hollows to which they lead they germinate and push their
minute roots into the cellular texture.” Such an explanation, however
plausible at first sight, fails on examination, from the fact that the
spores are too large to find ingress by such minute openings. It is
improbable that the _spores_ enter the growing plant at all. The
granular contents of the spores may effect an entrance either through
the roots or by the stomata, or the globose bodies produced upon the
germination of the spores may be the primary cause of infection. We are
not aware that this question has been satisfactorily determined. It is
worthy of remembrance by all persons interested in the growth of corn,
that the mildew is most common upon plants growing on the site of an old
dunghill, or on very rich soil. As the same _Puccinia_ is also to be
found on numerous grasses, no prudent farmer will permit these to
luxuriate around the borders of his fields, lest they should serve to
introduce or increase the pest he so much dreads.

The germination of the spores of the corn mildew is a very interesting
and instructive process, which may be observed with a very little
trouble. If the spores be scraped from the sori of the preceding year
(we are not sure that those of the current year will succeed), and kept
for a short time in a damp atmosphere under a glass receiver, minute
colourless threads will be seen to issue both from the upper and lower
divisions of the spores. These will attain a length several times that
of the spores from whence they spring. The extremities of these threads
ultimately thicken, and two or three septæ are formed across each,
dividing it into cells, in which a little orange-coloured endochrome
accumulates. From the walls of each of these cells, or joints, a small
pedicel, or spicule, is produced outwards, the tip of which gradually
swells until a spherical head is formed, into which the orange-coloured
fluid passes from the extremities of the threads.[4] A quantity of such
threads, bearing at their summits from one to four of these
orange-coloured, spherical, secondary fruits, supply a beautiful as well
as interesting object for the microscope. When matured, these globose
bodies, which Tulasne has called _sporidia_, fall from the threads, and
commence germinating on their own account. It is not impossible that the
sporidia, in this and allied genera, may themselves produce a third and
still more minute fruit, capable of diffusion through the tissues of
growing plants, or gaining admission by their stomata. Nothing of the
kind, however, has yet been of certainty discovered.

Footnote 4:

  Similar in all essential particulars to the germination of _Aregma_
  (Plate III. fig. 45).

Forty other species of _Puccinia_ have been recorded as occurring in
Great Britain, to all of which many of the foregoing remarks will also
apply—viz., such as relate to their two-celled spores being found
associated with, and springing from, the same mycelium as certain
orange-coloured one-celled spores; and also the main features of the
germinating process.


[Illustration:

  Plate IV.
  W. West imp.
]


A very singular and interesting species is not uncommon on the more
delicate grasses, being found chiefly confined to the leaves, and
produced in smaller and more rounded, or but slightly elongated, patches
(Plate IV. fig. 60). We have met with it plentifully amongst the turf
laid down in the grounds of the Crystal Palace at Sydenham, and also on
hedge-banks and in pastures. The spores are rather smaller than those of
_Puccinia graminis_, but, like them, much elongated, slightly
constricted, and borne on persistent peduncles. The most prominent
distinction may be found in the apices of the spores, which, in this
instance, are not attenuated, but crowned with a series of little
spicules, or teeth, whence the specific name of _coronata_ has been
derived (Plate IV. fig. 62).

The Labiate family of plants and its ally the Scrophulariaceæ are also
subject to the attacks of several kinds of Brand, a name, by the bye,
often applied locally to the corn mildew and other similar parasites,
and which may have originated in the scorched or _burnt_ appearance
which the infected parts generally assume. In the former natural order
the different kinds of mint, the ground-ivy, the wood-sage, and the
betony, and in the latter, the water figwort and several species of
veronica, or speedwell, are peculiarly susceptible; and on most a
distinct species of _Puccinia_ is found. To provide against doubt which
the less botanical of our readers may possess of the meaning or value of
the term _Puccinia_, which has already occurred two or three times in
this chapter, a brief explanation may be necessary, which more
scientific readers will excuse.

In botany, as in kindred sciences, acknowledged species have their
trivial, or specific name, generally derived from the Latin. In the last
species referred to, this was _coronata_, meaning _crowned_, in
reference to the coronated apex of the fruit. Any indefinite number of
species with some features in common are associated together in a group,
which is termed a _genus_, and the term prefixed to the specific name of
each species constituting that genus is its generic name, also commonly
derived from the Latin or Greek. In this instance it is _Puccinia_,
derived from the Greek _puka_, meaning _closely packed_, singularly
applicable to the manner in which the spores are packed together in the
pustules. The common features, or generic distinctions, of this genus,
are uniseptate spores borne on a distinct peduncle.

In returning to the species found on Labiate plants, let us suppose
ourselves to have strolled towards Hampstead Heath, and south of the
road leading from Hampstead to Highgate, near certain conspicuous and
well-known arches, built for a purpose not yet attained, are two or
three muddy ponds nearly choked up with vegetation. Some fine autumnal
afternoon, we must imagine ourselves to have reached the margin of the
most northern of these ponds, and amidst a thick growth of reeds,
sedges, and other water-loving plants, to have found the water-mint in
profusion and luxuriance, with every leaf more or less occupied, on its
under surface, with the yellow spores of a species of rust
(_Trichobasis_) mixed with the browner septate spores of the mint brand
(_Puccinia Menthæ_). This is common also on the horse-mint and
corn-mint; we have found it on the wild basil and wild thyme, and once
only on marjoram. Having collected as many leaves as we desire, and
returned to home and the microscope, we proceed to examine them in the
same manner as we have already examined the mildew, and as a result of
such proceeding arrive at the following conclusions:—The pustules are
small and round, never elongated as in the corn mildew, and generally
confined to the under surface of the leaves (Plate IV. fig. 69). The
spores are subglobose, slightly constricted, and the two cells nearly
two hemispheres, with their flat surfaces turned towards each other
(fig. 70). The form delineated in figure 75 is that of the sorus of many
of the epiphytal brands, the centre being occupied by the closely-packed
spores, surrounded to a greater or less extent by the remains of the
ruptured epidermis.

Although the species of Puccinia (_P. glechomatis_) found on the leaves
of the ground-ivy is said to be very common, we sought it in vain
amongst every cluster of that plant met with during last summer and
autumn, until, nearly despairing of finding it at all, we at last
encountered a plot of ground-ivy covering the ground to the width of two
or three yards, and in length eight or ten, nearly every plant being
attacked by the _brand_. This was in the corner of a pasture, and the
only time we found infected plants. The fungus, however, may be as
common as the plant in other localities. The pustules on the leaves are
larger than those of the mints, and also confined to the inferior
surface (fig. 73). The spores are elliptic and but slightly constricted;
the apex is often pointed, though not always so much as in our figure
(fig. 74).

Of other species found on allied plants we have not considered it
necessary to give figures, or write much. The betony brand (_P.
Betonicæ_, DC.) does not seem to be common enough to be readily found by
any one desiring to examine it for himself; and the same may be said of
the figwort brand (_P. Scrophulariæ_, Lib.), the wood-sage brand (_P.
Scorodoniæ_, Lk.), and the speedwell brand (_P. Veronicarum_, DC.); all
of these are, however, characterized by a distinct feature, or features,
which have been considered of sufficient importance to constitute a
separate species.

We have had occasion to refer incidentally to the brand found on the
under surface of the leaves of the wood-anemone (_P. Anemones_, P.).
This is one of the earliest and commonest species. Go wherever the
wood-anemone abounds, in any of the woods lying immediately to the north
of the metropolis, or any of the woods in Kent, and from March to May it
will not be difficult to find attenuated, sickly-looking leaves, with
the under surface covered with the pustules of this brand, looking so
like the sori of some fern (fig. 65) that it _has_ been, and still _is_,
sometimes considered as such. In Ray’s “Synopsis” (3rd edition, 1724),
it is described in company with the maidenhair and wall-rue ferns; a
figure is given of it in the same work (t. iii. fig. 1), and it is
stated,—“this capillary was gathered by the Conjuror of Chalgrave.”
When, afterwards, it was better understood, and the spots came to be
regarded as true parasitic fungi, it still for a long time continued to
bear the name, not even yet quite forgotten, of the Conjuror of
Chalgrave’s fern.

An examination of the spores, both collectively in the pustules, and
separately under a high power, will not fail to convince any one who has
examined only the species we have already alluded to, that this parasite
on the anemone (_P. Anemones_) is a true _Puccinia_, and a most
interesting one. The two cells of the spores are nearly spherical, and
the constriction is deeper and more positive than in any of the
preceding. Moreover, the surface of the spore is minutely and
beautifully echinulate, or covered with erect spines (Plate IV. fig.
66). Some few other of the species found in Britain have echinulate
spores, but those are not common like the present. One word of caution
to the amateur in search of the _Puccinia_ on the anemone. It will be
fruitless looking for it on the large foliaceous bracts of the
flower-stalk, since these may be turned up carefully, till the back
aches with stooping, ere a solitary pustule will be found; but the true
leaves, proceeding from the rhizomes, are certain soon to afford you
specimens.

Everybody knows the dandelion, but it is not every one who has noticed
the fungi found upon its leaves. These are most commonly of two kinds,
or probably the unilocular and bilocular forms of the same species: the
latter we have found in the month of May, and the former in August and
September. The lower leaves of young seedlings have generally rewarded
us with the best specimens of the septate-fruited brand (_Puccinia
variabilis_, Grev.). The pustules occur on both sides of the leaf, and
are very small and scattered (fig. 82). The spores are singularly
variable in form: sometimes both divisions are nearly equal in size;
sometimes the upper, and sometimes the lower, division is the smallest;
occasionally the septum will be absent altogether; and more rarely, the
spores will contain three cells. From the very variable character of the
spores (fig. 83), the specific name has been derived.

No species in the entire genus makes so prominent an appearance as the
one found on the radical leaves of the spear thistle (_Carduus
lanceolatus_). This latter plant is exceedingly abundant, and so is its
parasite (_Puccinia syngenesiarum_, Lk.). From the month of July till
the frosts set in we may be almost certain of finding specimens in any
wood. The leaves have a paler roundish spot, from one-twelfth to
one-fourth of an inch in diameter, on the upper surface, and a
corresponding dark brown raised spot on the under surface, caused by an
aggregation of pustules, forming a large compound pustule, often partly
covered with the epidermis. The individual pustules are small, but this
aggregate mode of growth gives the clusters great prominence, and
therefore they are not easily overlooked (Plate IV. fig. 63). Although
not confined to this species of thistle, we have not yet found this
_Puccinia_ on any other plant. The spores are elliptical, rather
elongated, constricted, and without spines (fig. 64).

Other species of _Puccinia_ are found on Composite plants, but with none
of these is the present fungus likely to be confounded, if regard be had
to its peculiar habit. The leaves, for instance, of the common knapweed
(_Centaurea nigra_) are often sprinkled with the small pustules of the
centaury brand (_Puccinia compositarum_, Sch.); these generally occupy
the under surface of the lower radical leaves (fig. 67); occasionally a
few of the pustules appear on the upper surface. We have not often found
this fungus in the neighbourhood of London on the leaves of the
knapweed, but, on the other hand, we have encountered it very commonly
on those of the saw-wort (_Serratula tinctoria_). The spores are oval,
scarcely constricted, and not attenuated in either direction (fig. 68).
Other Composite plants than those above named are liable to attacks from
this parasite.

In our school-days we remember to have spent many a stray half-hour
digging for “earthnuts,” under which name we, as well as our elders and
betters, knew the tubers of _Bunium flexuosum_. Not then, nor for many
years after, did we notice, or regard if we did notice, the distorted
radical leaves and leaf-stalks, and the blackish-brown spots, which
reveal the cause in the presence of a brand, or parasitic fungus, of
this genus (_Puccinia Umbelliferarum_, DC.), which is extremely common
on this, as well as some other allied plants. If any spot is searched
where this plant grows in any profusion, before the flowering stalks
have made their appearance above the surrounding grass, this _Puccinia_
will be readily found by the twisted, contorted, sickly appearance of
the infested leaves (fig. 71), the petioles of which are often swollen
and gouty in consequence. The sporidia are shortly stalked, and
generally very much constricted (fig. 72). The species found on the
stems of the hemlock, and also that on Alexanders (_Smyrnium
Olusatrum_), are distinct; the spores of the latter being covered with
tubercles or warts (figs. 55, 56). During a botanical ramble through
Darenth Wood in April of the year just passed away, in some parts of
which the sanicle abounds, we found the bright glossy leaves of this
singular and interesting plant freely sprinkled with the pustules of a
_Puccinia_ (_P. Saniculæ_, Grev.), which is not at all uncommon on this,
but has not hitherto been found on any other plant. Dr. Greville, of
Edinburgh, was the first to describe this, as well as many other of our
indigenous minute Fungi. For many years he has toiled earnestly and
vigorously at the lower cryptogams, as evidenced by his “Scottish
Cryptogamic Flora,” published in 1823; and yet his continual additions
to the records of science show him to be earnest and vigorous still.

We have by no means exhausted the catalogue of Fungi belonging to this
genus found in Britain, nor even those commonly to be met with; but the
fear of prolixity, and the desire to introduce a description of other
forms into the space still remaining to us, prompt us to dismiss these
two-celled brands with but a brief allusion to such as we cannot
describe. Box-leaves are the habitat of one species, and those of the
periwinkle (Plate VI. fig. 132) of another. One vegetates freely on the
leaves of violets through the months of July and August, and another
less frequently on the enchanter’s nightshade. Several species of
willow-herb (_Epilobium_) are attacked by one _Puccinia_ (Plate IV.
figs. 78, 79), and a single species by another. Plum-tree leaves,
bean-leaves, primrose leaves, and the half-dead stems of asparagus, have
their separate and distinct species, and others less commonly attack the
woodruff, bedstraw (Plate VIII. figs. 172, 173), knotgrass, ragwort, and
other plants less common, more local, or, to the generality of the
non-botanical, but imperfectly known.

We have found, not uncommonly in the autumn, the scattered pustules of a
brand on the stems and leaves of the goat’s-beard, occupying the places
which were scarred with the remains of cluster-cups that had flourished
on the same spots a month or two previously (Plate IV. fig. 76). The
pustules are by no means minute, but elongated and bullate; the spores
beautifully studded with warts (Plate IV. fig. 77). This species cannot
certainly be identical with _Puccinia compositarum_ (Schlecht), _P.
syngenesiarum_ (Lk.), or _P. tragopogonis_ (Corda). In none of these do
the spores appear to be warted, and the habits of both the latter are
different. Its nearest associate appears to be _P. centauriæ_ (Corda),
at least in the fruit, and whilst the form and character of these organs
are considered of any value in the determination of species, smooth
spores cannot be associated, we think, with tuberculate or echinulate
spores under the same name.

In the spores of the species to which attention has been more specially
directed we have types of the principal forms. In the “corn-mildew” they
are elongated, and tapering towards either end; in the “coronated brand”
the apex is crowned with spicular processes; in the “wind-flower brand”
the entire spores are echinulate; in the “mint brand” they are globose;
in the “composite brand” elliptic; in the “earth-nut brand,” nearly cut
in two at the septum; and in the “dandelion brand,” so variable in form
that no two are precisely alike. On the other hand, all are
characterized by a transverse septum dividing each spore into two cells.


------------------------------------------------------------------------



                               CHAPTER V.

                           _COMPLEX BRANDS._


FROM the twin-spored genus we pass to another, in which the spores are
usually divided into three cells, and which, from this cause, has been
named _Triphragmium_. Only one species has hitherto been found in this
country, and _that_ not very commonly, on the leaves of the
meadow-sweet, _Spiræa ulmaria_ (Plate III. fig. 47). Externally, it much
resembles, in the size and character of the pustules, many of the
above-named brands, but when seen under the microscope this similarity
disappears. In general outline the spores are nearly globose, and
externally papillose. In one species, found on the Continent, but not
hitherto in Great Britain, the spores are covered with curious
long-hooked spines, by means of which they adhere tenaciously to each
other. In germination, the spores of _Triphragmium_ do not offer any
noteworthy deviation from those of _Puccinia_,[5] and the chief interest
of our indigenous species lies in the three-celled form of its spores
(fig. 48), to which occasionally those of _Puccinia variabilis_
approximate, and may be regarded as the link which unites the two
genera.

Footnote 5:

  Mr. Currey has only seen the tips of the germinating threads swell,
  and become septate, each of the joints thus formed falling off and
  germinating without producing spherical sporidia; whilst Tulasne
  figures globular sporidia, as will be seen in our fig. 49, reduced
  from the figure by Tulasne.—(_Vide_ Currey, in “Quarterly Journal of
  Microscopical Science,” 1857, pp. 117, &c.)

The old story of “Eyes and no Eyes” is too often literally true, not
only with the children it was written to amuse and instruct, but also
with children of a larger growth who scorn such baby tales, and disdain
such baby morals. Out of more than a thousand indigenous species of
microscopic fungi, of which there is generally some evidence afforded of
their presence visible to the naked eye, how few are there of the
millions that inhabit our island who can count twenty species that they
have ever seen; still fewer that have noticed one hundred. Amongst the
twenty species known to the few will probably be included one which
appears in autumn in prominent black spots, the size of a large pin’s
head, or half a turnip seed, with the flat face downwards, sprinkling
the under surface of blackberry leaves (fig. 39); with larger, reddish,
purplish, or reddish-brown spots on the upper to indicate the presence
of the fungus beneath. Just at the time when blackberries are ripe,
these spots are in perfection on the leaves, and _their_ eyes must have
been sadly at fault who could ever have gathered their own blackberries
without seeing the discoloured leaves. The coloured spots on the face of
the leaf are due to the diseased state of the tissues caused by the
parasite on the opposite surface. As much of the leaf as contains two or
three of the black pustules should be removed carefully with a knife or
sharp scissors, and submitted to microscopical examination; each will be
seen to consist of a dense tuft of blackish, elongated, stalked bodies,
clustered as in fig. 44, but much more numerously and closely packed
together. These are the spores of the blackberry brand (_Aregma
bulbosum_, Fr.). A few of these spores should be removed on the point of
a sharp penknife, placed on a glass slide with a drop of distilled water
or alcohol, covered with thin glass, and then viewed with a quarter-inch
objective. Each spore has a stalk longer than itself, thickened below,
and containing a yellow granular core. The spore itself is much longer
than in any of the _Pucciniæ_, of a dark brown colour, and apparently
divided by several transverse partitions into three, four, or more
cells, the whole surface being covered with minute warts or prominences
(Plate III. fig. 41).

In 1857, Mr. F. Currey investigated the structure of these spores, and
the results of these experiments were detailed in the “Quarterly Journal
of Microscopical Science.” One conclusion arrived at was, that “the idea
of the fruit consisting of sporidia united together and forming a chain,
is certainly not in accordance with the true structure. The sporidia are
not united to one another in any way, but, although closely packed for
want of space, they are in fact free in the interior of what may be
called a sporangium or ascus.” To arrive at this conclusion, careful
examination was necessary, and new modes of manipulation essential. The
details of one method employed were to the following effect:—A
sufficient number of spores were removed on the point of a lancet, and
placed on a slide in a drop of alcohol. Before the spirit was quite
evaporated, two or three drops of strong nitric acid were added, and the
whole covered with thin glass. The slide was then warmed over a
spirit-lamp, the acid not being allowed to boil, but only gradually
heated to boiling point. By this means the fruit was found to consist of
an outer membrane, nearly transparent, and studded with tubercles; that
this membrane enclosed a number of cells which constituted the apparent
joints, and which were naturally flattened at either end by mutual
pressure. When the outer membrane was dissolved or ruptured, these cells
escaped, and became detached from each other. The cells, thus set free,
exhibited a brownish or yellow ring around a paler area, in the interior
of which an inner cell was visible, sometimes globular, often irregular
in shape. The examination of the ring was not entirely satisfactory; it
appeared to be sometimes marked with concentric lines having the
appearance of wrinkles. The inner cell had granular contents and a
central nucleus. When perfectly free they were spherical in form, with a
distinct membrane of their own; and colourless, except when acted upon
by reagents. The means employed to determine the existence of these
cells was to soak the spores in muriatic acid; then, upon pressure of
the glass cover, the outer membrane and ringed cells were ruptured, and
the inner cell escaped (Plate III. fig. 46).

Germination may be induced in these spores by keeping them in a moist
atmosphere (fig. 45); but the mode does not differ from that described
above as occurring in the “corn mildew.” Mr. Currey writes:—“I know no
microscopical object of greater beauty than a number of fruits of
_Phragmidium_ in active germination.” By _Phragmidium_ he means the
_Aregma_ of this work, of which _Phragmidium_ is a synonyme.

Well may the reader remark on arriving thus far, “Does all this
examination and detail refer to the fruit borne in the little blackish
spots on bramble leaves, which I have hitherto overlooked?” Ay, and to
several similar spots on other plants. Examine carefully the raspberry
leaves in your garden, and you will probably find similar, but smaller,
pustules also on the under surface (Plate III. fig. 42). We say
_probably_, because none of our British species seem to be equally
uncommon with this. During the past year we examined hundreds of plants,
and did not find a single pustule. This species was named by Dr.
Greville _Aregma gracilis_, which name it still continues to bear (fig.
43). Such a fate will not await you if you should proceed in the autumn
to some chalky district where the burnet is common. Go, for instance, to
Greenhithe or Northfleet, on the North Kent Railway, in August or
September, where the burnet is plentiful, and the leaves will present
the appearance of having been peppered beneath, from the number of
minute pustules of the burnet brand scattered over the under surface
(fig. 30, upper leaflets). Or if you prefer collecting nearer home,
visit some neighbouring garden, if your own does not contain many roses,
and the leaves will be found equally prolific in an allied species (fig.
36). Should gardens and roses be alike unattainable, any bank or wood
will furnish the barren strawberry (_Potentilla fragariastrum_), and
during the latter part of the summer, or in autumn, another species of
_Aregma_ will not be uncommon on the under surface of the leaves (fig.
33). All these species will be found accompanied by the orange spores of
species of _Lecythea_, which some mycologists consider to be distinct
fungi, and others to be merely forms or conditions of _Aregma_. These
spores are represented in Plate III. figs. 31, 34, 37, and 40. From the
magnified figures of the spores of the different species of _Aregma_
(figs. 32, 35, 38, 41, and 43), it will be apparent that they have all
certain features in common, _i.e._, cylindrical spores containing from
three to seven cells. This may be called the _generic_ character, common
to all the species of the genus _Aregma_. Again, each species will be
observed to possess its own distinct features, which may be termed its
_specific_ character. In one, the apex of the spores will be obtuse, in
another acutely pointed, in another bluntly pointed, &c. In one species
the number of cells will usually be four, in another five or six, in
another seven or eight. The stem in one species will be slender and
equal, in another thickened or bulbous. So that in all there will be
some permanent peculiarity for each not shared by the others.

One other form of brand (_Xenodochus carbonarius_), presenting, it is
believed by some, generic differences from all that we have as yet
noticed, remains to be briefly alluded to. This form appears to be very
uncommon in this country, but, when found, is parasitic on the leaves of
the great burnet (_Sanguisorba officinalis_), a plant of local
distribution. The parasite appears to the naked eye in small tufts or
pustules resembling those of an _Aregma_, but, when microscopically
examined, the cells of the spores are found to be numerous, indeed,
considerably more than in the most complex _Aregma_ (fig. 29). This,
however, seems to be the only distinction, for the cells are free in the
interior of the investing membrane, and in all points of structure, in
so far as it has been examined, identical with _Aregma_. Whether it is
logical to consider a four-celled spore an _Aregma_, and a seven-celled
spore an _Aregma_, and exclude a ten or twelve-celled spore from the
same genus on account of the number of its cells, does not appear to us
clearly answerable in the affirmative.

During the course of this and the preceding chapter we have passed
rapidly through four genera of parasitic fungi so nearly allied, that
one is almost led to doubt the validity of the generic distinctions.
These may be presented briefly thus:—

             Spores two-celled         PUCCINIA.

             Spores three-celled       TRIPHRAGMIUM.

             Spores four to            AREGMA.
             seven-celled

             Spores many-celled        XENODOCHUS.

It has been seen that the habit, mode of growth, germination, and
structure, except in the number of cells, scarcely differ; but it is not
our province here to enter upon the discussion of such a subject.

The association of one-celled, orange-coloured spores with the brown two
or more celled spores passed in review is another feature worthy of a
passing notice, and which opens a field for discussion. It is generally
admitted that these two forms are the production of the self-same
mycelium or vegetative system, but it is not so generally admitted that
they are but two forms or phases of the fruit of the same plant. It is
not at all uncommon in the history of mycology to find two forms which
were for a long time considered to be distinct plants producing
different forms of fruit, and which bore different names, and were
located in different genera, at length proved to be only the self-same
plant in different conditions, and ending in one name being expunged
from the list. Such a fate probably awaits, at no distant date, the
orange spores which precede or accompany the species in the present
genera. Already Tulasne and some others accord them no place in their
system.

It may be added, for the benefit of any who wish to pursue the study of
this interesting branch of Cryptogamic Botany, that the leaves of the
plants containing the parasitic fungi now noticed may be collected and
preserved by drying between folds of blotting-paper, or the leaves of a
book, and will retain their character, with the exception of colour in
the orange forms, so as to be eligible for examination at any period of
the year for twenty years to come. Each species, when dry, may be
transferred to an old envelope, and labelled outside with the name, date
of collection, and locality; and one hundred such envelopes will
constitute a miniature herbarium in a very small compass.


------------------------------------------------------------------------



                              CHAPTER VI.

                                _SMUTS._


ONE of the fungal diseases of corn long and widely known has obtained
amongst agriculturists different appellations in different localities.
In some it is the “smut,” in others it is respectively “dust-brand,”
“bunt-ear,” “black-ball,” and “chimney-sweeper,” all referring, more or
less, to the blackish soot-like dust with which the infected and
abortive ears are covered. This fungus does not generally excite so much
concern amongst farmers as the other affections to which their
corn-crops are liable. Perhaps it is not really so extensively
injurious, although it entirely destroys every ear of corn upon which it
establishes itself. Wheat, barley, oats, rye, and many grasses are
subject to its attacks, and farmers have been heard to declare that they
like to see a little of it, because its presence proves the general
excellence of the whole crop. No one who has passed through a field of
standing corn, after its greenness has passed away, but before it is
fully ripe, can have failed to notice, here and there, a spare,
lean-looking ear, completely blackened with a coating of minute dust
(Plate V. fig. 98). If he has been guilty of brushing in amongst the
corn, it will still be remembered how his hands and clothing became
dusted with this powder; and if at the time he should have been clad in
sombre black, evidence will have been afforded—in the rusty-looking tint
of the powder when sprinkled upon his black continuations—that, however
sooty this powder might appear whilst still adhering to the ears of
corn, it has an evident brown tint when in contact with one’s clothes.
This powder, minute as it is, every granule of it constitutes a spore or
protospore capable of germination, and ultimately, after several
intermediate stages, of reproducing a fungus like the parent of which it
formed a part. During the growth of the plant its virulent contents flow
like a poison through the innermost tissues, and at length attack the
peduncle or axis of the spikelets of the ear, raising up the essential
organs and reducing them to a rudimentary state. Brongniart, who made
this species the special subject of observation, states that the fleshy
mass which is occupied by the fungus consists entirely of uniform
tissue, presenting large, almost quadrilateral cavities, separated by
walls, composed of one or two layers of very small cells filled with a
compact homogeneous mass of very minute granules, perfectly spherical
and equal, slightly adhering to each other, and at first green,
afterwards free or simply conglomerate towards the centre of each mass,
and of a pale rufous hue; at length the cellular walls disappear, the
globules become completely insulated, and the whole mass is changed into
a heap of powder, consisting of very regular globules, perfectly alike,
black, and just like the reproductive bodies of other fungi (Plate V.
fig. 99). A scientific botanist of some repute, M. Unger, published a
work in Vienna during the year 1823, in which he sought to prove that
this, and allied species of fungi, were not fungi at all, but merely
broken up cells, or disruptured and altered conditions of certain
portions of the diseased plants. The most satisfactory refutation of
this theory may be found in the fact that the spores of the smut can be
seen to germinate under favourable conditions, and produce fruit,
whereas, if they were only the ordinary cells of the plant broken up by
disease, fructification would not take place.

The spores in this species are exceedingly minute. It has been
ascertained that forty-nine of them would be contained within a space
the one-hundred-and-sixty-thousandth part of a square inch; hence one
square inch of surface would contain little less than eight millions.
These myriads of spores are shed from the ears, and nothing remains but
the barren matrix in which they were borne when the farmer proceeds to
gather in his crops. At that time he sees no more of the “smut,” all
remembrance of it for the time is gone, his only thought is to stack his
corn in good condition. But the millions of spores are dispersed, ten
millions at least for every ear that has been “smutted,”—and will they
not many of them reappear next year, and thus year after year, with as
much certainty as the grain upon which they are parasitic?

Like many of the parasitic fungi, so destructive in the farm and the
garden, this species belongs to the family in which the spores are the
distinctive feature. After many botanical changes, the “smut” is at
length regarded as a fixed resident in the genus _Ustilago_; with the
specific name of _segetum_, which latter signifies “standing corn;” it
is therefore the _Ustilago_, or _smut of the standing corn_. The
characters of the genus are, chiefly, that the spores are simple and
deeply seated, springing from delicate threads, or in closely-packed
cells, ultimately breaking up into a powdery mass. Fifteen members of
this genus have been described as British. One of these (_U. maydis_)
attacks the maize or Indian corn grown in this country in a similar
manner as the common smut attacks wheat or barley; but as maize is not
an established crop with us, a more minute description of this species
is unnecessary; the spores are figured in Plate V. fig. 108. Another
species (_U. hypodytes_) makes its appearance at first beneath the
sheaths of the leaves surrounding the stems of grasses (fig. 100), and
ultimately appears above and around them as a purplish-black dust (fig.
101). The seeds of sedges, the leaves and stems of certain definite
species of grass, the flowers of scabious (Plate VI. figs. 123-125), the
receptacles of the goatsbeard, the anthers of the bladder campion, and
other allied plants, and the seeds of the Bistort family, are all
liable, more or less, to the attacks of one or other of the residue of
the fifteen species of _Ustilago_ already referred to as indigenous to
Britain.


[Illustration:

  Plate V.
  W. West imp.
]


Although we do not profess to teach practical men how to grow good corn,
or how they shall get rid of, or keep clear from, the many foes to which
their crops are exposed, yet a suggestion may be offered, based upon the
facts obtained in our botanical researches, supported by the analogy of
allied circumstances. In this instance the extreme minuteness and
profusion of the spores would evidently render all the corn liable to
the attachment of, perhaps only two or three, spores to the seed coat.
Some ears of corn in nearer proximity to the smutted ears may be covered
with spores which yet remain invisible to the naked eye, and when these
grains are mixed with others in the heap, the chances are not much in
favour of any handful not becoming charged with spores. If the majority
of these were not redeemed from destruction by the many changes,
shiftings, rubbings, and scrubbings to which the seed corn is liable
between the time of its reaping and the period of its sowing, we might
expect a very large crop of “smutted” corn. Under ordinary circumstances
we can scarcely imagine that the loss arising from infected ears would
repay much special labour to prevent it, only that to a large extent the
precautions taken to cleanse the seed corn from the spores of one fungus
will also avail for another, and while cleaning it of the spores of
“smut,” those of “bunt” will also be removed. The facts that we rely
upon chiefly as indicating the remedy are that the spores are only
superficially in contact with the seed corn, and that they are of less
specific gravity, causing them to float on the surface of any fluid in
which the corn may be immersed. Again, the spores of many species of
fungi will not germinate after saturation with certain chemical
solutions. One of the most successful and easy of application is a
strong solution of Glauber’s salts, in which the seed corn is to be
washed, and afterwards, whilst still moist, dusted over with quick-lime.
The rationale of this process consists in the setting free of caustic
soda by the sulphuric acid of the Glauber’s salt combining with the
lime, and converting it into sulphate of lime. The caustic soda is fatal
to the germination of the spores of “bunt,” and probably also of “smut;”
although, as already intimated, except in cases where these affections
of the corn are very prevalent, we shall be informed by the
agriculturist that the cost of labour in the prevention will not be
compensated in the cure.

Experience has also taught us that many fungi flourish in proportion to
the wetness of the season, or dampness of the locality. A wet year is
always exceedingly prolific in fungi, and a dry season correspondingly
barren, at least in many kinds, whilst others, as the experience of 1864
has convinced us, are exceedingly common. In a field or wood the
mycologist reaps his richest harvest of mycological specimens in the
lowest and dampest spots, in swamps, ditches, and ill-drained nooks.
This is a fact worth knowing as much by the farmer as the amateur
botanist in search of specimens for his herbarium.

One of the most unmistakable species of “smut” is that which infests the
goatsbeard, on which we have already described an _Æcidium_. Generally
about the same time as the cluster-cups make their appearance on the
leaves, some of the unopened flower-heads of this plant will be found
considerably altered in appearance by the shortening of the segments of
the involucre, and at length by the whole inflorescence being invested
with a copious purplish-black dust. If, by any means, the lobes of the
involucre are any of them separated, the enclosed dust escapes,
blackening the fingers and clothing of the collector, as if it were soot
(Plate V. fig. 92). A little of this dust submitted to the microscope
will be found to consist of myriads of small globose spores, nearly
uniform in size and shape; and if a higher power be employed, each of
these will appear to have a papillose or minutely granulated surface.
The florets, dwarfed in size and contorted, or the remains of them, are
embedded in the mass of spores (fig. 93), and if one or two of these are
removed and placed under a good one-inch objective, every part will be
found covered with adhering spores, to the apparent exhaustion of its
substance. Of course, the florets are never developed when subjected to
the attack of “smut.” The whole plant assumes a faded, sickly
appearance, even before the spores are fully ripened. We would recommend
our readers, if they collect one of the infected flower-heads, to put it
into a box or paper by itself, for if placed in the box with other
specimens it will so sprinkle them with its black powder as to render
them nearly useless for microscopic examination: everywhere the
microscope will detect, where the unaided eye failed to recognize a
trace, the ubiquitous spores of _Ustilago receptaculorum_ (Plate V. fig.
94).

In the fenny districts of the eastern counties a species of “smut”
called _Ustilago typhoides_ attacks the stems of reeds, forming thick
swollen patches of several inches in length (fig. 128), sometimes
occupying the whole space between two joints or nodes, and lying beneath
the sheath of the leaves. The spores in this species are larger than in
the species which attacks the culms of grasses in a similar manner
(Plate VI. fig. 129).

There are not many features in the rest of the species of this genus of
sufficient interest to the general reader or microscopist to render it
advisable to furnish any detailed account of them. We may, however, note
that in a species found on the leaves of the common cock’s-foot grass
the spores are large, obovate, and rough, with minute granules (figs.
117, 118). This species is known botanically as _Ustilago_ _salveii_,
and externally bears considerable resemblance, except in the size and
colour of the spores (fig. 119), to another species much more common,
and which occurs on the leaves of _Poa aquatica_ and _P. fluitans_. The
last-named species forms long parallel sori, extending often for several
inches along the leaves of the aquatic grasses just named, giving them a
very singular appearance (Plate V. figs. 105, 106). The spores are small
(fig. 107), not being more than one-fourth the length of the last
species, and smooth, whilst those are minutely granulated.

An interesting species occurs, very rarely, on the stems of such grasses
as _Aira cæspitosa_ and _A. aquatica_. The sori are in bands at regular
distances apart (Plate VI. fig. 120), each band being composed of a
number of short parallel sori (fig. 121). The spores are not more than
one-third of the size of those in _U. longissima_.

Sedges are also subject to attack from other species of smut; one of
these (_U. olivacea_) appears to convert the seeds into a fine
olive-coloured dust (Plate VI. fig. 126), which gives to the fruit a
similar appearance to that presented by corn when attacked by _Ustilago
segetum_. Another species, which also absorbs the seeds, becomes
hardened and consolidated more than in any other species, and, though
larger than the normal seeds, still retaining their form (figs. 109,
110). This is _Ustilago urceolorum_, the spores of which are also
figured (fig. 111).

The beaksedge (_Rhyncospora alba_) suffers from an allied species which
affects it in a similar manner (Plate V. figs. 96, 97), but is not
equally common. The spores of _Ustilago utriculosa_, found on different
species of _Polygonum_, instead of being granulated, are reticulated on
the surface (Plate VI. figs. 114, 116). The chief interest attaching to
_Ustilago antherarum_ consists in its habitat, for it is developed in
the anthers of the flowers of the bladder campion, and other plants of
the same natural order. The anthers are much swollen and distorted by
this parasite, which is not uncommon, though easily overlooked unless
specially sought after (Plate V. figs. 102-104). A list of all the
British species will be found at the close of this volume. It will be
noted that as in the genus _Æcidium_ the prevailing colour of the spores
is orange, so in the genus _Ustilago_ it is black, with a purplish or
violaceous tinge.

Four diseases in wheat of fungal origin are known and recognized in the
popular language of the farm as “mildew,” “rust,” “smut,” and “bunt.”
Sometimes one and sometimes another is most prevalent, and he is an
exceedingly fortunate individual who can walk through his fields and
find only one of them, especially if that one should be sparingly
distributed. It has been our good fortune to dwell much amongst
cornfields, and the terror of the word “mildew” to a farmer’s ears is
not unfamiliar in our reminiscences of the past, ere we discarded the
much-loved country to become a dweller in town. The subject of our
present remarks inspired no such alarm in the districts of our
experience, but in some seasons and localities it is certainly one of
the “pests of the farm.” Under the different appellations of “bunt,”
“pepper brand,” “bladder brand,” and sometimes “smut,” this infection is
very generally known. Externally there is no appearance, except to the
practised eye, that anything is wrong. There is no black impalpable dust
about the ears as in the true “smut,” no red withered leaves or spotted
stem as in the “rust” and “mildew,” and no stunted growth or
malformation, evident to the casual glance, by which the insidious foe
can be recognized; but stealthily and secretly the work is accomplished,
and until the “bunted” grains make their appearance in the sample, the
disease may, perchance, be unchallenged.

Externally the “bunted” grain is plumper, and whilst the corn is still
green these will be of a brighter green than the rest (Plate V. fig.
84). When broken, the farinaceous interior will be found replaced by a
minute black dust of a very fœtid, unpleasant odour, and greasy to the
touch (fig. 85). This powder constitutes the spores of the “bunt” mixed
with myceloid threads. It may happen that much of the corn in a field is
“bunted,” and the discovery not made till the wheat is being ground for
flour; then the odour and colour will speedily decide the produce to be
unfit for human food. We have not the least doubt that “bunted” corn,
when ground with flour, is injurious in proportion to its extent, whilst
at the same time we can scarcely conceive an intelligent miller grinding
up a sample containing any large proportion of “bunted” grains in
ignorance of the fact.

If we break open a grain of wheat infested with the “stinking rust” or
“bunt,” and then place some of the powder in a drop of water on a glass
slide, and submit this to the microscope, first using the half-inch
power, then the quarter, or fifth, and finally an eighth or tenth, we
shall find that this minute dust consists of myriads of globose brown
bodies termed spores, which possess certain reproductive functions.
These spores will be found mixed with a number of delicate branched
threads, to which they are attached by a short stalk or pedicel, visible
with the higher powers (fig. 86). The surface of the spores you will
also observe to be beautifully reticulated. These features just
described as visible in the “bunt” are the characteristics of the genus
to which it belongs (_Tilletea_), and of which it is the only British
species. An allied species infests the Sorghum or durra, a grain but
little cultivated in Europe, but found extensively in Africa and Asia,
and also apparently found on the _Bajra_ of India.

The interesting experiments of the Rev. M. J. Berkeley on the
germination of “bunt” spores have been already alluded to. They were
undertaken shortly after the outbreak of the potato disease, to
ascertain, if possible, the mode by which the minute spores of fungi
inoculate growing plants; and although at that time only a bare
suspicion of the nature of the bodies resulting from the germination of
“bunt” spores was entertained, succeeding examinations in the same
direction have brought to light extraordinary facts, and manifested the
progress of the successive developments of four generations. The spores
of “bunt” are larger than those of the different species of “smut,” and
reticulated on the surface (Plate V. fig. 86). When these are made to
germinate a kind of stem is protruded (fig. 87), upon which small
clusters of elongated thread-like spores of the second generation, or
sporidia, are produced (fig. 88). After a time these spores conjugate,
or become united by short transverse processes in the same manner as has
been observed in some of the lower forms of Algæ (fig. 89). The
conjugated spores in the next stage germinate and produce a third kind
of fruit, different from either of the preceding, and constituting a
third generation (fig. 90). These in turn germinate and produce a fourth
order of reproductive organs (fig. 91), so that in the process of growth
the “bunt” spores evidently pass through four generations. Hence, as one
result, the number of germinating bodies is greatly increased, as well
as their power of inflicting injury in a corresponding diminution in
size. There are still many points in the history of the growth and
development through successive generations of the “bunt” spores, but
enough is known, on the one hand, to show that this is a true vegetative
parasite, and not merely a diseased condition of the tissues of the
wheat plant, and on the other that it is perfectly distinct from all the
phases of the other and similar parasitic fungi which affect the wheat
crop.


------------------------------------------------------------------------



                              CHAPTER VII.

                            _COMPLEX SMUTS._


SOME of the microscopic fungi are the most unpromising and uninteresting
objects to the naked eye which could well be imagined. No one would
suppose that the black dust so profusely shed in such genera as
_Ustilago_ and _Polycystis_ could be better than as much soot; unless he
has learnt by experience not to judge by appearances, but to suspend
judgment until examination. The axiom will sooner or later force itself
upon all who examine minute objects with the microscope, that all
organic nature, whether animal or vegetable, increases in interest in
proportion to the magnifying power. Seen by the unaided eye, _moulds_
are all nearly alike, and they seem to be “moulds” and nothing more.
“Smuts,” again, sometimes attack one organ, and sometimes another, with
very little variation in colour; and “rusts” are all “only rusts” with a
paler or more intense rusty tint, until the marvellous combination of
lenses, so appropriately named a _microscope_, unfolds a new world, and
exposes its new inhabitants unparalleled in the old world of larger
life, in form, habit, development, and mystery.

A very interesting, though small group of fungi, allied to the
preceding, are included botanically under the genus called _Polycystis_,
in allusion to the many cells of which the spores are composed.[6] In
the most recent work on British Fungi, approximating to a Flora—viz.,
“Berkeley’s Outlines”—only three species are recorded, whilst the most
common, at least around London, is omitted in error; for it could
scarcely have been unknown as indigenous to this country. This last is
the crow-foot smut (_Polycystis pompholygodes_, Lev.), found on the
leaves and petioles of the common creeping buttercup (_Ranunculus
repens_), distorting them very much, and also occurring on the
wood-anemone and some other Ranunculaceous plants. The leaves and their
footstalks, when attacked, become swollen, as if blistered at first, and
ultimately burst in an irregular manner, exposing a mass of blackish
soot-like dust (Plate IX. fig. 183), which on examination will be found
to consist of the many-celled spores alluded to (Plate IX. fig. 184).
Each of these spores appears to have a transparent outer membrane,
either enclosing an unequal number, from two or three to five or six,
distinct cells, compressed together into a spherical form by the outer
integument, or the interior is divided by septa into as many cells. Each
of these divisions contains a dark brownish endochrome, or
cell-contents. As may be anticipated, the spores in all the species
associated in this genus are interesting objects for the microscope. The
species on the buttercup may be found through the summer and autumn on
_Ranunculus repens_, especially whenever that plant is met with in very
damp situations. We have seldom found the plant in any profusion without
its attendant fungus.

Footnote 6:

  Rabenhorst has proposed _Urocystis_ as the name of this genus, on the
  ground that _Polycystis_ was priorly applied to a genus of Algæ.

Another species of these many-celled smuts is not uncommon in gardens,
on the sweet violet, attacking the footstalks of the leaves more
commonly than the leaves themselves, and swelling and contorting them
(Plate IX. fig. 185). In general structure the spores are very similar
to those of the last species, save that the cells are smaller, and a
larger number are collected together (Plate IX. fig. 186). So far as we
have yet examined the spores of this and the preceding species, they
appear to consist of separate and distinct vesicles (probably spores),
contained within a hyaline sac or outer membrane, and _not_ to be a
single spore divided into cells by numerous septa.

A species of equal interest (_Polycystis Colchici_, Tul.) is found on
the autumnal crocus, or meadow-saffron (_Colchicum autumnale_). The
spores approach nearer to those of the last than of the prior species.

A fourth species occurs on the leaves of rye (Plate IX. fig. 187),
forming elongated parallel blackish lines (_Polycystis parallela_, B. &
Br.). It has also been found on the leaves of some grasses, but does not
appear to be very common.

Many similar features are possessed by the two members of a genus named
_Tubercinia_, which have been found in this country. One of the species
is parasitic upon a plant which we who inhabit southern England never
meet with, but which is not uncommon in Scotland, _i. e._, _Trientalis
Europæa_. The parasite attacks the leaves about the month of September,
forming bullate or blistered patches one-eighth to one-sixth of an inch
broad, containing a mass of black spores (Plate III. fig. 52). These
spores are irregularly globose, large, and opaque, consisting of a
number of distinct cells (Plate III. fig. 53). Never having seen other
than dried specimens—kindly communicated by Dr. Dickie of Aberdeen, the
discoverer of this species—we cannot add much to its history beyond the
published description by the Rev. M. J. Berkeley.

The other species occurs on potatoes, and is, during some seasons,
common in all parts of Great Britain. The spores are curious, being
composed of a number of cells arranged in the form of a hollow sphere,
with one or two apertures communicating with the interior (Plate III.
fig. 54). They are generally attached by a delicate thread. This
species, sometimes confounded with the potato scab, was first described
by Mr. Berkeley, about the time of the appearance of the “potato
disease,” with which, however, it is in no way connected.

Thus it will be seen that, inasmuch as we have complex brands in which
the number of cells are considerably increased, so have we “complex
smuts” in which, instead of one cell, we have many. In the last instance
the two genera associated together in this chapter agree. The spores in
both are distinctly cellular, but in the last genus far more opaque and
consolidated than in the first. Whilst it may be doubted whether the
compound spores of _Polycystis_ are anything more than a number of
individual spores with a gregarious habit, invested with an outer
membrane, such a hypothesis cannot (as far as our individual
examinations extend), be made to include _Tubercinia_. No doubt has yet
been thrown on the genuine character of either of these genera. No
_Uredo_ or _Æcidium_, no _Trichobasis_ or _Puccinia_ has been
ascertained or suspected to appear as a prior or subsequent form. In
their supposed integrity they offer an interesting study, and in their
development a good subject for investigation.


------------------------------------------------------------------------



                             CHAPTER VIII.

                                _RUSTS._


UNFORTUNATELY, this group of fungi contains species but too well known
for their ravages amongst graminaceous plants, especially the cereals.
“Corn rust,” as it is generally called, has a reputation little better
than mildew, and it really deserves no better, for it is only another
form of that pest of the farm, from the mycelium of which the
corn-mildew is at length developed. There are two species very closely
allied (doubtless only forms of the same species with different spores)
which attack the leaves and culms of growing corn, and, bursting through
the cuticle in the manner represented in Plate VII. fig. 141
(magnified), give a peculiar rusty appearance to the plant, as
represented in Plate VII. fig. 140. One of these corn-rusts is
botanically named _Trichobasis rubigo-vera_ (Lev.), or the “true rust
_Trichobasis_;” the latter, which is the generic name, being a compound
of two Greek words (_thrix_, a hair, and _basis_, a foundation), on
account of the spores being at first furnished at their base with a
short, thread-like peduncle, which at length falls away (Plate VII. fig.
142). The other Corn rust is _Trichobasis linearis_, or “line-like
_Trichobasis_,” because the sori or pustules are linear, or lengthened
out like a line; the spores nearly double the length of those of the
other Corn rust (Plate VII. fig. 144), and not so bright in colour. By
intermediate forms these two rusts pass insensibly the one into the
other, so that it is sometimes difficult to distinguish them. Both have
the spores clustered together in the pustules, at first (Plate VII. fig.
143) attached by their peduncles, but they soon become free, and are
scattered like rust-powder over the plant. Adverting to the attack of
rust upon the wheat crops to an unusual extent a few years since, the
Rev. M. J. Berkeley wrote as follows:—

    We have seen rust more prevalent in white wheats, especially in
    the variety called Russian white, which has red smooth chaff,
    than we ever remember it. It is, however, confined to particular
    spots; and while in one field not a single leaf is free,
    insomuch that a person walking through the wheat is completely
    painted with the spores, of a fine rust-red; an adjoining field,
    separated only by a hedge, has not a rusty leaf. So long,
    however, as the rust is confined to the leaf, it is, we believe,
    perfectly harmless. The grain swells in spite of it, and the
    only effect is that the flag dies a little earlier, which is not
    undesirable when it is too luxuriant. If, however, it gets to
    any extent upon the chaff, much more if it attacks the seed
    itself, as is sometimes the case, it is very mischievous.


[Illustration:

  Plate VI.
  W. West imp.
]


    There is, indeed, a notion that rust is merely a form of mildew,
    and this may be true; but if so, it is a harmless form. The true
    rust (_T. rubigo-vera_), if a form of mildew, preserves its own
    characters to the end, and merely presents a second form of
    fruit, a circumstance which is exceedingly common amongst the
    lower fungi. It may exist in company with the mildew, but it
    also more frequently is developed without a trace of mildew
    intermixed. As far, then, as its immediate effects upon the
    plant go, it may be treated as a distinct parasite, though
    advanced botanists may look upon it as offering a case of what
    they call dualism, which may be easily understood on a
    comparison with such plants as marigold and orache, which
    produce seeds of two different forms. Its ultimate effects may,
    indeed, be injurious, as, if it be really a second form of
    mildew, it is capable of propagating that pest. The case is
    quite different with _Trichobasis linearis_, which is in fact
    merely the young state of the mildew. When once that supposed
    species makes its appearance, it is quite certain that there
    will be mildew to a greater or less extent. While the spores of
    the one remain unaltered, though intermixed with the true
    bipartite spores of the mildew, the other exhibits every
    intermediate state of form and colour.

M. Tulasne, to whom we have already alluded as a high authority on this
subject, is of opinion that all the species enumerated in this group or
genus, are mere conditions of other species, and therefore excludes it
altogether. Another genus (_Lecythea_), for the same reason, has shared
the same fate.

It must not be forgotten that twenty-eight species of rust belonging to
this genus are now recorded as occurring in Great Britain. Some of these
have yellow or yellowish spores; the rest have the spores of a decidedly
brown colour. One of the most attractive of the yellow-spored species is
that which appears on the groundsel (_T. Senecionis_), and a good notion
of its external appearance may be gained from our figure (Plate VII.
fig. 145). It is not always to be found without searching closely, for
in some localities we have found it very sparingly, whilst elsewhere—as,
for instance, on Wandsworth Common—we have met with it as soon or as
late as there were groundsel leaves for it to grow upon. No spot or
change in the appearance of the upper surface of the leaves indicates
the presence of the parasite beneath; this is, however, often betrayed
by the golden-yellow streaks which appear on the stem. Many a time and
oft the boys in the semi-rural districts about town have marvelled and
questioned each other concerning the reason why, in gathering
“groundsel” for the little bird at home, we should be so particular, and
pass so many promising plants, plucking here and there a leaf, and
seldom collecting one which they consider eligible for the purpose.
Collectors of minute fungi must expect to overhear occasionally even
hints touching their sanity from those who, without the remotest idea of
their mission, think they must be slightly “wrong in the head” to gaze
so narrowly and intently, amongst nettles, groundsel, grass, or dry
leaves, and only take an occasional fragment of a rotten stick, or two
or three sickly leaves, carefully deposit them in their wallet, hat, or
pocket, and then “move on.”

It will be unnecessary to repeat what has been stated in a former
chapter on spermogones. It will be remembered that these organs are
found developed in connection with some of the species of the present
genus, as well as with the cluster-cups, or _Æcidiacei_. They consist
externally of small conical elevations, pierced at the apex, which
contain minute, cellular, linear bodies called spermatia, invested with
a kind of mucous substance, that over-flows with them from the orifice
of the spermogone, like lava from the crater of a miniature volcano. The
rust in company with which they have been found most plentifully, is
that which covers the under surface of the leaves of the commonest of
all thistles (_Cnicus arvensis_). The external form of one of these
spermogones is figured Plate VII. fig. 153. The rust possesses, when
fresh, a peculiar odour, which is said to resemble that of
orange-flowers; whence was derived its name of “sweet-smelling rust”
(_Trichobasis suaveolens_, Lev.). M. Tulasne writes:—“With respect to
this species, it is, in my opinion, but the first form of a _Puccinia_,
analogous to _P. Compositarum_, D.C.: the spermogones with which it is
mixed being very abundant, it ought to be placed with that _Puccinia_. I
should, perhaps, retain some doubts upon the legitimacy of this
relationship, if it had not been my fortune to meet on another species
of the same kind (_Puccinia Anemones_, P.) spermogones perfectly
characterized, and in which the colour, habit, and position would not
allow me to hesitate an instant in attributing them to the _Puccinia_.”
In this species of rust the whole under surface of the leaf is covered
with a purplish-brown dusty coating of the spores, from the numerous
pustules which are produced (Plate VII. fig. 151). The plants, when
attacked, have a paler and more sickly appearance; the leaves have a
tendency to fold backwards at their margins, and thenceforth their
growth seems to be determined. Sowerby, in his “British Fungi,”
says:—“Two or three sorts of flies are occasionally found dead on this
plant at the time of the fungus being upon it, which is after wet
weather in the summer, or early in autumn; being apparently tempted by
its flavour, they over-eat themselves, or else are destroyed by some
poison.” This rust has spores resembling, in general characters, those
of the yellow-spored series Plate VII. fig. 152).

We have not thought it necessary to give figures of many species, partly
on account of the uncertainty existing in many minds whether they ought
to be regarded as species, and whether they will long claim a place in
the British Flora; and partly on account of the similarity which exists
between them, at least so far as they are of interest to the
microscopist only.

During the autumn of last year, whilst on a botanical excursion through
a portion of Epping Forest, the “great bog” became a centre of some
interest. Bogs are generally attractive spots to those who are in search
of microscopic organisms. On this occasion the chief objects of interest
were the small brown pustules (Plate VIII. fig. 168) with which the
upper surface of a large number of the leaves of the pennywort
(_Hydrocotyle vulgaris_) were sprinkled. These pustules were brown,
orbicular, regular, and in habit seemed to resemble rather those of most
of the _Pucciniæ_ than of a _Trichobasis_. The large, vigorous, and
healthy leaves were less affected. Microscopical examination, at first
incomplete, led us to the conclusion that it was a species of _Uredo_,
which had been met with in France (_Uredo Hydrocotyles_, Mont.); but a
re-examination, to which we were prompted by Mr. Currey, led to the
conclusion that it belonged rather to the present genus; but it can
scarcely be associated with any species already described,
notwithstanding its apparent affinity with the brown rust found on
umbelliferous plants, in which the pustules are invariably developed on
the _under_ surface. Under these circumstances, we have called it the
Pennywort rust (_Trichobasis Hydrocotyles_), whilst still doubtful
whether it is not the same fungus as that described by Montagne, with
whose description it agrees in everything, except what is implied by the
generic name. It should not be forgotten, that the work in which
Montagne first described this species was published when the genus
_Uredo_ embraced the present genus, which was separated from it by
Leveille twelve years later; and it is possible that this species was
included in a more recent work by the same author, in error and without
re-examination, under the old name. An examination of authentic
specimens of Montagne’s plant would settle the point; but we know of no
published collection which contains it. The characteristic difference
between the two genera lies in the presence of a peduncle in the early
stage of _Trichobasis_ Plate VIII. fig. 169), and its absence in all
stages of _Uredo_. Without wandering further into a subject which has
not the merit of being very popular, let us away to some green lane in
search of violets, and having found them, take a little of the brown
dust from one of the small pustules on the leaves, upon the point of a
penknife; place this, with a drop of water, upon a glass slide, and make
a record of what we observe.

The field is covered with the myriad spores of a rust of a nearly
spherical shape, brownish in colour, and here and there one with a short
transparent colourless stalk or pedicel. This is the violet rust
(_Trichobasis Violarum_, B.), very common all through the summer and
autumn, generally on the under surface of the leaves of violets, in
woods and hedgerows. Should it so happen that the spores when placed
under the microscope are found to be two-celled, it will prove that
instead of a rust, or _Trichobasis_, being under examination, a brand,
or _Puccinia_, has been found, which is almost equally common, and which
may, without such a test, be easily mistaken for a rust. According to
the theory of di-morphism, this is the higher form or complete fruit of
the same fungus, which in its simple-celled state is called _Trichobasis
Violarum_.

A similar circumstance may befall the student in examining the rust of
labiate plants (_Trichobasis Labiatarum_, Lev.), which occurs on
different species of mint, especially the water-mint, about the month of
August. We have found a few of the two-celled spores of the _Puccinia_
imbedded in the pustules of this rust almost constantly, whilst the
one-celled spores are not uncommon in the pustules of what is regarded
as the true mint brand (_Puccinia Menthæ_, P.).

In spring the young leaves of the periwinkle (_Vinca major_) will, in
some situations, become thickened considerably, and ultimately browned
on both faces with the pustules of a rust (_Trichobasis Vincæ_), which
though covered with a conidioid dust are often very tardy in bursting
the epidermis. It is almost impossible, after the pustule is ruptured,
to find one in which the bilocular spores of _Puccinia_ (fig. 132) are
not largely intermingled with the unilocular spores of the “rust” (Plate
VI. fig. 131). Later in the season by two or three months, other leaves
of the same plants will be found occupied by the smaller and more widely
scattered pustules of _Puccinia Vincæ_, in which the unilocular spores
of the “rust” will seldom be found. In this instance the leaves are
scarcely thickened, and the colour of the spores is much darker. The
under surface of the leaves is commonly alone occupied, and
corresponding paler spots on the upper surface indicate the presence of
the parasite beneath.

The garden and field bean is liable in some seasons to become quite
rust-coloured in consequence of the profusion of spores with which the
leaves and stems are covered, from the bean rust (_Trichobasis Fabæ_,
Lev.), which in like manner is considered as the simple stage or form of
the bean brand (_Puccinia Fabæ_, Lk.). If the legumes are also examined,
a few pustules will sometimes be found on them. Beans thoroughly
infected with this rust or brand are seldom of much service in either
field or garden.

Beetroot, or mangold wurzel, is another example of garden and field
produce which is subject to a similar visitation. This rust often has
very red spores when produced on red varieties of beet. During
September, 1863, it (_Trichobasis Betæ_, Lev.) was sent us on the leaves
of the wild beet (_Beta maritima_).

All the species of _Polygonum_ are exceedingly subject to the attacks of
the Persicaria rust (_Trichobasis Polygonorum_, B.), which nearly covers
the leaves, till the entire plants seem to be smothered in Scotch snuff.
If it were allowable to affirm of any plants that they are martyrs to
parasitism, such might be said of the Persicarias and their allies.


[Illustration:

  Plate VIII.
  W. West imp.
]


Sedges are subject to the attacks of a rust much resembling the corn
rust. When it occurs on some species of _Carex_, the upper surface of
the leaf has corresponding pale spots, and the pustules themselves are
surrounded by a yellowish margin. This species (_Trichobasis caricina_)
is far from uncommon (Plate VIII. figs. 170, 171). The sedge-like plants
belonging to the genus _Luzula_ have also their own species of rust
(_Trichobasis oblongata_), the spores of which are deeper in colour than
in the sedge rust (Plate VII. figs. 158, 159).

Amongst the remaining species of _Trichobasis_ (the reader must pardon
our using the generic name, as we have no equivalent), that found on the
leaves of various composite plants is the most common (_Trichobasis
Cichoracearum_, Lev.). It occurs on some thistles, on the saw-wort,
dandelion, several species of hawkweed, and similar plants. The pustules
are small and more diffused than in the species found on _Cnicus
arvensis_, and they as often appear on the upper as on the lower
surfaces of the leaves.

On umbelliferous plants three species are recorded; one with yellow
spores (_Trichobasis Petroselini_, B.); another with a blistered habit,
and brown, ovate, or oblong spores (_T. Umbellatarum_, Lev.); and a
third with tawny, obovate, or egg-shaped spores (_T. Heraclei_, B.),
which is found solely on the cow-parsnip. The species of _Puccinia_
corresponding to some of these species of _Trichobasis_ are known, but,
in other cases, probability, or speculation if you please, occupies the
place of knowledge.

During the month of September, 1864, it was our good fortune to spend a
week in revisiting the scenes of our boyhood, and exploring the minute
botany of one of the marshy districts of East Norfolk. One day of the
seven, memorable to us for the discovery of three specimens of a large
Boletus (_B. cyanescens_),[7] not found, to our knowledge, since the
days of Sibthorpe, was further enriched by a species of _Trichobasis_,
new to Britain, and apparently uncommon on the Continent. This rust was
found on the leaves of the “grass of Parnassus” (_Parnassia palustris_)
on a narrow strip of marsh near Irstead church. It was sought in vain
elsewhere. The leaves were scarcely changed in appearance, except by the
presence of the pustules. There were no discoloured spots, but the
pustules appeared sometimes plentifully, more often scattered, on both
surfaces of the leaves: they were small, of a bright brown, with oval
spores; the latter were, in their early stages, shortly stalked. We have
called this species _Trichobasis Parnassiæ_. It is possibly the same as
published by Westendorp in his “Herbier Cryptogamique Belge” as _Uredo
Parnassiæ_, but we know of no copy which we can consult, and have failed
in discovering any other species to which we can refer it. It is
certainly a _Trichobasis_ and not an _Uredo_, according to the present
limitation of the latter genus.

Footnote 7:

  Two of these specimens were found at the bottom of a hedge-bank,
  amongst grass, by the side of the road leading from Neatishead-street
  to Irstead Rectory, and the third in a similar position by the Norwich
  road, two hundred yards from the turning which leads to
  Neatishead-street.

Although the evidence against the retention of the species of _Lecythea_
(as the genus is named) amongst Fungi as true species, on the ground of
di-morphism, is even stronger than against the group just illustrated,
we cannot pass them altogether in silence, especially in a popular
treatise. Those who are residents in town, and yet possess their little
plot of garden-ground, with only two or three pet roses, may have had
the misfortune of seeing them smothered with a yellow blight. This
golden visitation, unwelcome as it is, may afford a subject for the
microscope, and for a small space in this chapter. At first there will
not appear to be any important difference between the spores of the
yellow series of the last genus and those of the present; but a closer
examination will reveal one important distinction, viz., the presence of
colourless elongated, abortive spores. The species are not so numerous
by half as those of _Trichobasis_, even when three anomalous forms are
included, which species are included by some mycologists in two other
genera. One very common rust of this group has already been alluded to
(Plate II. fig. 37), and which is known botanically as _Lecythea Rosæ_.
A similar one is found on the bramble, and another on the burnet. All
these three species are produced at first on spots which are afterwards
more or less occupied by the long, many-celled spores of the dark brown
brands called _Aregma_ or _Phragmidium_, between which and the simple
yellow spores of the rust almost every intermediate form may often be
found in the same pustule. Thus, from the same mycelium as that of the
rose rust, the rose brand is afterwards developed; whilst from the nidus
of the bramble rust (Plate III. fig. 40) the bramble brand is also at
length produced; and the successor to the burnet rust (Plate III. fig.
31) is the burnet brand. Besides these, a rust belonging to the same
genus may be found on the leaves of the poplar, the spurge, and the
common valerian, and two or three species on willows. It can scarcely
have escaped notice, that the goat-willow is almost constantly afflicted
with a rust on the under surface of the leaves (Plate VIII. fig. 160).
This species will again come under notice as the summer spores of a
truly dimorphous species.

One of the rusts separated by some botanists from this genus is found
(possibly most commonly) on the leaves of the raspberry; but during the
past autumn we have met with it plentifully on the upper surface of the
leaves of one or two species of bramble, and have never seen it growing
on the raspberry, although in all descriptions of the species that is
stated to be its habitat. Even to the naked eye this is so distinct,
that no one could well confound it with any other. It appears very late
in the autumn, and the spots are scattered at some distance apart from
each other (Plate VIII. fig. 162); each spot or pustule forming a ring
(Plate VIII. fig. 163 enlarged) encircling a cluster of spermogones
which occupy the centre.

Another rejected species (_Lecythea Lini_, Lev.) occurs on the little
purging flax (_Linum catharticum_), forming small pustules on the leaves
(Plate VIII. fig. 165); these burst irregularly, and remain surrounded
by the remains of the ruptured epidermis (Plate VIII. fig. 166). The
yellowish spores are subglobose (Plate VIII. fig. 167), and in the first
instance concatenate, or chained together like a necklace, which
circumstance has been taken advantage of to place it, with one or two
other species, in a separate genus.

We cannot claim for the species brought into notice in the present
chapter any attractive features resulting from singularity of form,
complexity of structure, or delicate tracery, whereby they might commend
themselves to mere “searchers after curiosities,” or be recommended from
friend to friend as “sensation” objects for the microscope. They _do_
possess an interest and a value, but such as would not be appreciated by
those who seek to pass an idle half-hour by gazing at some new thing.


------------------------------------------------------------------------



                              CHAPTER IX.

                                _RUSTS._


A QUARTER of a century ago, and all the fungi enumerated in the
preceding and in the present and following chapters would have been
arranged under three genera, called respectively _Æcidium_, _Puccinia_,
and _Uredo_. Under the last-named genus all the species illustrated in
the present chapter, beside many others, would have found “a habitation
and a name.” There are still a few which bear the old generic name, and,
if only out of respect, we shall grant them the first place.

Let the first bright day in May witness the student beside a cluster of
plants of _Mercurialis perennis_, which it will not be difficult to find
in many localities, and, on turning up the lower leaves, he will meet
with our first illustration of a genuine _Uredo_, in the form of yellow
confluent patches, with a powdery surface (Plate VII. fig. 133). This
will be _Uredo confluens_. By the way, the generic name is in itself
suggestive, which it always should be in all instances, but
unfortunately is not; it is derived from the Latin word _uro_, “I burn,”
and is peculiarly applicable in instances where the leaves acquire a
blistered, burnt, or scorched appearance, occasioned by the presence of
the fungus. The microscopical features of the spores of this genus are,
briefly, a more or less spherical form, without any pedicel or footstalk
Plate VII. fig. 134). These spores are at first produced each in a
separate cell, but when ripe become free, and are at times with
difficulty distinguished from such forms as _Trichobasis_, unless the
pedicels in the early stage of the latter genus are regarded.

A rare species in Britain is the oak-leaf rust (_Uredo Quercus_), in
which the sori or pustules are minute, and at first yellow, but
afterwards orange. It occurs on the under surface of the leaves, and
was, we believe, first found in this country by Mr. D. Stock, in the
neighbourhood of Bungay, nearly five-and-twenty years since. That
gentleman informs us that it was not at all uncommon, but always
appeared on the young shoots which had sprung up from the trunks or
roots of trees that had been cut down. We are uncertain whether it has
been found by any one since that time in this country, although it is
not uncommon in France.

The leaves of the common sorrel are often sparely sprinkled with the
pustules of a rust (_Uredo bifrons_, Grev.), which derives its specific
name from the fact that the pustules, which appear on both surfaces of
the leaves, are often opposite to each other Plate VII. fig. 137). These
pustules are generally seated on a discoloured spot (Plate VII. fig. 138
enlarged), and are surrounded by the remains of the ruptured epidermis.
The spores are globose and brown Plate VII. fig. 139). We have not met
with any other _Uredine_ on the sorrel leaves, though one having a
similar appearance to the naked eye is not uncommon on several species
of dock.

The fern rust (_Uredo Filicum_), which occurs on the under surface of
the fronds of two or three species of ferns, we have never met with, and
do not think that it can be considered common. It has been found in the
West of England, on _Cystopteris_, and Sowerby collected it, probably
not very far from London.

One of the most common is the rust found on the leaves of the
enchanter’s nightshade (_Circæa lutetiana_), sometimes nearly covering
the under surface with its tawny snuff-coloured spores Plate VII. fig.
135). The plant on which it is found is rather local, but the rust
(_Uredo Circææ_) seems to abound wherever the plant on which it is
parasitic flourishes. Another fungus of a very similar external
appearance may be collected, more rarely, from the leaves of the same
plant; but in this the spores are two-celled, or divided by a transverse
partition. This fact is mentioned to guard against disappointment,
should the spores be found to differ from the characters of this
section, and to show that the microscope is essential to the study of
fungi. The spores of the true Uredo are globose and without any
partition Plate VII. fig. 136).


[Illustration:

  Plate IX.
  W. West imp.
]


We may also observe that a very interesting species may be found on
several species of St. John’s-wort (_Hypericum_), but especially on the
under surface of the leaves of the Tutsan, covering them with its
golden-coloured spores (Plate VIII. fig. 174). Another occurs on the
leaves of some of the wild garlics (_Allium_); one is not uncommon on
some of the stitchworts; another on saxifrages; another on willow-herbs
(_Epilobium_), and one on the leaves of the cowberry. All of these have
yellowish spores. A species with brown spores occurs on sea-lavender
(_Statice_). Space to write on our own part, and patience to read on the
part of others, induce us to dismiss all these species with the bare
allusion to them and the plants on which they may be found. Some of them
may occur in one locality and some in another, and enough has perhaps
been said to enable any one to place any that he may find in the proper
genus, if not with the scientific name.

From the numerous instances we have met with of persons wholly
disinterested in the subject, collecting and making inquiries concerning
the bright orange patches next to be referred to, we are led to conclude
that most persons have, at least, seen them. These patches of
orange-coloured powder burst through the cuticle, and appear on the
young branches of wild roses, extending sometimes for two or three
inches in length Plate VII. fig. 147), and form one of the most
beautiful and obtrusive of the dust-like fungi. It is not confined to
roses; but the meadow-sweet, on which it is also found, does not grow in
localities where its parasite is so liable to meet the gaze of the
ordinary wayfarer. The habit of this rust is more or less that of those
which are associated with it. The pustules are not small and orbicular
as in most instances in other groups (except _Polycystis_), but are
large and irregular, and generally but few together or single. The
spores are variously coloured, and have peduncles, or footstalks, of a
greater or less length. In the rose rust these spores are profuse, but
the peduncle is short (Plate VII. fig. 148).

Plants of the pea and bean tribe are liable to be attacked by one of
these rusts, and in this instance the spores are so characteristic that
no one could well confound them with any other. Externally it appears as
an irregular brownish pustule, breaking through the epidermis and filled
with an impalpable powder, not unlike a pinch of “brown rappee” snuff.
The spores are ovoid, with a very long peduncle, whence its name
(_Uromyces appendiculata_). It appears on a great variety of plants, but
from the peculiarity of the spores Plate VII. fig. 150), is easily
recognized. Our figure represents it on the leaf of a vetch (Plate VII.
fig. 149). Almost at the commencement of this volume (Chap. III.) we had
occasion to refer in detail to some experiments made by De Bary on the
spores of this species. In the remarks then made occurs a recommendation
of reperusal, which would obviate any repetition here.

An allied species, and a beautiful one, is to be found on the stinking
iris (_Iris fœtidissima_), and another on the under surface of the
leaves of primroses.

The pilewort (_Ranunculus ficaria_) we have already seen attacked by one
species of microscopic fungi, and we have now to record the occurrence
of another. Some plants appear to be destined both alive and dead to
become the prey of others. The common nettle, for instance, as if in
retribution for the annoyance it often occasions on account of its
stinging propensities, has not less than twenty different species of
minute fungi, to say nothing of coleopterous and lepidopterous insects,
which make a home, sometimes upon its green leaves, and sometimes on its
dead stems. We might almost state that it has a flora and a fauna of its
own. The pilewort, too, has many foes; but these are fewer in number,
and mostly attack the living plant. The cluster-cups have been already
noticed; some do not fall within the limits of this volume, but one,
which is found in May and June, belongs to the present genus. It appears
like a purplish-brown powder bursting through blistered spots on the
leaves and footstalks Plate VII. fig. 156). The spores are small, and
are, of course, provided with pedicels Plate VII. fig. 157).

The under surface of the leaves of the white Dutch clover are often
sprinkled with black spots, which are nearly round and very numerous.
These are so many clusters of fungi belonging to a different section, in
which the threads are the important feature. But another parasite is
also found on leaves of the same plant, in which the pustules are far
less numerous and regular, and are often found on the petiole as well as
the leaf, distorting them and twisting them in various directions Plate
VII. fig. 154). This is the clover rust (_Uromyces apiculata_, Lev.),
which is a parasite on numerous plants, being found also on the great
water-dock and other kinds of dock. The spores are ovoid and brown, with
a short peduncle (Plate VII. fig. 155). A very beautiful species occurs
on the leaves of the ladies-mantle (_Alchemilla_), but hitherto we have
not been fortunate enough to collect it.

It can scarcely be too great an assumption to suppose that every one is
acquainted with the goat-willow (_Salix caprea_), or that every
schoolboy knows the birch (_Betula alba_). It may be proceeding a step
too far to affirm that all who know these trees well enough to
distinguish the one from the other, will have observed the under
surfaces of the leaves of both sprinkled with a golden dust, during the
summer months, and which are the spores of a parasitic fungus. So common
is this orange-coloured powder on leaves of the trees above-named, that
we can hardly believe any one to have had a branch of either in his hand
and not observed it, provided any leaves adorned the branch in question.
What this parasite is, and what its associates, it is our province to
endeavour to explain. Our figure (Plate VIII. fig. 160) represents a
leaf of the sallow or goat-willow, with the under surface exhibiting
yellow patches, consisting of spores, which are magnified in the next
figure (Plate VIII. fig. 161). This exceedingly common rust is termed
_Lecythea caprearum_, Lev., when in the condition figured; but in
reality this is only the summer stage, bearing the summer fruit of
_Melampsora salicina_, which latter attains its mature development on
the same leaves in the succeeding winter (Plate IX. fig. 191) or early
spring. Of course this latter remark applies to the fallen leaves, for
at this period all the willows and other deciduous trees are bare. But
the leaves, before they fall, give evidence of the parasite at work; and
if the collected decaying mass of rubbish at the base of sallow bushes
be examined about March, these leaves will be found bearing upon them
mature heaps of elongated, wedge-shaped spores, closely packed side by
side (Plate IX. fig. 192), and which, whilst still adherent, may often
be found in active germination, as represented in an allied species at
the bottom of our plate (Plate IX. fig. 197). This phenomenon consists
in the production of cylindrical tubes, more or less elongated, from the
upper extremity (rarely from the base) of the prismatic spores. These
tubes are straight or twisted, simple or forked, and each of them
becomes divided by transverse septa into four unequal cells towards
their apex, from each of which is produced a spicule bearing a
sporidium, or spherical secondary fruit, in the same manner as in the
genera _Puccinia_ and _Aregma_. It should be observed, that the winter
spores of this rust are borne on the opposite surface of the leaves to
the summer spores: for whilst the latter are developed from the under
surface, the former are found on the upper. This being also an instance
of di-morphism, the summer condition, when spherical spores are
produced, should not be regarded as a distinct plant, and the name of
_Lecythea caprearum_ does not merit retention in the list of fungi.

There are five species of this interesting group, or genus, found in
Great Britain, to the residue of which we may only briefly allude. It
has already been stated that, in summer, the yellow spores of a rust are
found on the under surface of birch-leaves. These must be sought on the
young twigs or suckers, proceeding from the stumps of trees which have
been cut down: pale discoloured spots on the upper surface of the leaves
indicate the presence of the rust beneath. This is the _Uredo betulina_
of old authors (begging their pardons, for some of them still live), the
_Lecythea longicapsula_ of more recent times, and the summer spores of
_Melampsora betulina_, according to M. Tulasne and his disciples. When
fresh, it is reputed to exhale a faint odour, as of the primrose. During
the winter and spring months the wedge-like spores of the second crop
are matured on the fallen leaves (Plate IX. figs. 189, 190), and these
are capable of a speedy germination, and the production of secondary
reproductive bodies, as in the willow rust above alluded to.

Probably, also, the similar rust on the poplar (Plate IX. figs. 195,
196), or on the aspen, may be met with under like conditions; _i.e._,
the summer spores, which are yellow and spherical, on the living leaves,
and the brown permanent masses of winter spores on the fallen and
decaying leaves. The sole remaining British species is not uncommon on
leaves of the common spurge in gardens, and whilst the yellow
pulverulent spores occur on the upper, it will not be improbable that
black permanent spots will be found on the lower leaves (Plate IX. figs.
193, 194), enclosing closely-packed, rudimentary, elongated or
wedge-shaped cellules of the winter spores.

Any one may make himself acquainted with the genus _Coleosporium_ with
but little trouble, which the acquisition will more than compensate. A
summer stroll into any locality in which the common coltsfoot can be
found, will be certain to prove sufficient. Let the spot selected be any
station on the North Kent Railway, for those who reside in town, or even
a trip to the Crystal Palace and a stroll in the grounds, and when the
well-known leaves of the coltsfoot are descried, the under surface of
the first leaf will doubtless give proof of the presence of the fungus
in question, by the orange spores amongst its dense woolly hairs.
Sometimes the leaf is almost covered beneath with the bright
orange-coloured dust. This is the coltsfoot rust (_Coleosporium
tussilaginis_, Lev., Plate VIII. fig. 180), which may serve as a type of
the rest. It may be observed that a species of cluster-cup, or
_Æcidium_, with spores of nearly the same colour, is also to be found on
the leaves of the same plant; but in this case the upper surface of the
leaf has also corresponding purplish spots, and, what is of still more
importance, the spores are seated in small fringed cups. The rust is
common till the wintry frosts have set in, and is far more conspicuous
than the cluster-cups. A kind of di-morphism prevails in all the species
of this genus. Some of the pustules resolve themselves into a kind of
powder, whilst others remain entire and solid. Generally there is the
largest proportion of globose, dust-like, free spores, produced in the
earliest developed fungi, whilst they become more rare towards the close
of the season. The permanent spore-spots consist of obovate cellules
placed side by side, each of which is divided transversely by three or
four septa, and is filled with an orange-red endochrome (Plate VIII.
fig. 181); the exterior being enveloped in a kind of mucous layer. The
arrangement of spores when packed together in the pustule is shown in
Plate VIII. fig. 182, from an allied species. When these spores
germinate, which they do with great readiness, each division emits a
long tube, which generally remains simple and undivided, and from its
extremity is produced a reproductive body of an obovate or nearly
kidney-shape. These filaments are about 1/120th of an inch in length, of
a colourless transparent membrane, along which the orange-red contents
of the spores pass into the newly-formed sporidia, or reproductive
bodies by which they are terminated. Most of these reniform sporidia
disengage themselves from the filaments on which they are produced, and
either elongate themselves into a simple and uniform filament, or swell
at the extremity as if to reproduce a second spore. If the newly-formed
sporidia do not become free, they increase the length of their primitive
filament, which by a frequent repetition of the process becomes a tube
swelling out at unequal distances.


[Illustration:

  Plate X.
  W. West imp.
]


The summer spores, or pulverulent spores of the first generation, which
are analogous to the Uredospores of _Aregma_, are also capable of
germination, for, if placed in favourable circumstances, they will
develop very long filiform processes, which either remain simple or
become more or less branched, but always nearly uniform in their
diameter. M. Tulasne states that he has observed this germination many
times, though we have been less fortunate.

Of the six species of this genus known to occur in Great Britain, the
majority may be commonly met with. That very widely-diffused plant, the
wood cow-wheat (_Melampyrum pratense_), known well to all amateur
botanists for its pertinacity in drying black, and presenting anything
but an inviting appearance to claim for it a place in the herbarium—also
becomes the matrix for the development of a member of this genus;
_i.e._, the cow-wheat rust (_Coleosporium Rhinanthacearum_, Lev.), and
which is found on other allied plants, as the little eyebright
(_Euphrasia officinalis_), &c. (Plate VIII. fig. 176). In colour and
habit it resembles the last-named species, and its free, echinulate
spores (Plate VIII. fig. 177) form a pretty object for the microscope.

Another equally common species is found inhabiting the leaves of the
sow-thistles (_Sonchus arvensis_ and _S. oleraceus_), and in the autumn
may generally be found on either of those plants, presenting the
appearance delineated in our plate (Plate VIII. fig. 178). The permanent
spores resemble in many points those of the first species, as will be
seen from the figure from De Bary’s treatise on this subject (Plate
VIII. fig. 179). This is certainly one of the most showy of uredinous
fungi, and could not be well overlooked.

The butter-bur rust (_Coleosporium petasites_, Lev.) and the Campanula
rust (_Coleosporium Campanulæ_, Lev.) are found, the former on the
leaves of the butter-bur, and the latter on those of the harebell and
other _Campanulæ_, less frequently. We have, however, indicated
sufficient, since their great similarity in unprofessional eyes will
furnish, in one or two species, all that is desirable for the
microscopist.

Unless some similar plan to the following be adopted for examining the
species of this genus, it may result in disappointment; for the slight
attachment of the joints to each other will otherwise present only a
mass of simple echinulate cellules, if a portion be only removed from
the leaf on the point of a lancet. This method consists in making a thin
vertical section of a pustule in which the spores are contained; by this
means the arrangement of the fruit and the mucedinous threads from
whence they proceed may be observed. Any person possessed of the
cardinal virtues of microscopy—patience and perseverance—will be
rewarded in this instance; whilst those who are deficient will lose an
object worthy of the virtues they dare not boast. But few instances have
occurred in this and the preceding chapters in which the exercise of any
great ingenuity or application has been called for; the most juvenile or
truest tyro at the microscope may see for himself much of what has been
indicated, whilst a few opportunities have occurred for more practised
manipulists to prove that they are neither juveniles nor tyros.


------------------------------------------------------------------------



                               CHAPTER X.

                             _WHITE RUSTS._


ALLUSION has already been made to the important memoir recently
published by Dr. de Bary. “White rusts” occupy a conspicuous position in
that memoir, and the experiments therein detailed, with the conclusions
arrived at, will be largely drawn upon in furnishing the present
chapter. Whilst believing that we have fairly represented the views, and
faithfully narrated the story of research, if not literally, but denuded
of some technicality, yet in such manner as to convey the sense of our
author, we claim no originality or merit save for the garb in which it
appears, without addition, stricture, or confirmation of our own.

What is the external appearance presented by the “white rust” of
cabbages, and allied cruciferous plants, is soon told. During summer and
autumn it occupies the surface of the leaves and stems of the
shepherd’s-purse (_Capsella bursa-pastoris_), with elongated narrow
white spots like streaks of whitewash (Plate X. fig. 198), and later in
the season the leaves of cauliflowers and cabbages become ornamented
with similar patches, arranged in a circular manner (Plate X. fig. 199),
forming spots as large as a sixpence. Wherever these spots appear, the
plant is more or less deformed, swollen, or blistered, even before the
parasite makes its appearance at the surface. These white pustules have
a vegetative system of ramifying threads which traverse the internal
portion of the plants on which they are found: these threads constitute
what is termed the _mycelium_. Not only when the plant is deformed and
swollen with its undeveloped parasite do we meet with the threads of
mycelium in its internal structure, but also in apparently healthy
portions of the plant, far removed from the evidently infected spots.
These threads are unequal in thickness, much branched, and often with
thick gelatinous walls filled with a colourless fluid. They creep
insidiously along the intercellular passages, and are provided with
certain appendages in the form of straight thread-like tubes, swollen at
their tips into globular vesicles (Plate X. fig. 204). These threads do
not exceed in length the diameter of the mycelium which bears them. The
appendages communicate in their interior with the mycelium, and contain
within them the same fluid, which at length becomes more watery, and the
terminal vesicles have their walls thickened, so as to resemble, on a
casual observation, granules of starch. Dr. de Bary conceives that these
appendages serve a similar purpose to the tendrils or suckers of
climbing phanerogamic plants; _i.e._, to fix the mycelium to the cells
which are to supply the parasite with nourishment. As these appendages
are always present, it is easy to discover the mycelium wherever it
exists amongst the tissues of an affected plant.

The white pustules already alluded to contain the fruit of the parasite.
Bundles of clavate or club-shaped tubes are produced upon the mycelium
beneath the epidermis of the infested plant, forming a little tuft or
cushion, with each tube producing at its apex reproductive cells,
designated “conidia.” These conidia appear to be produced in the
following manner:—The tips of the clavate tubes generate them in
succession. At first a septum, or partition, divides from the lower
portion of the tube a conidium cell; this becomes constricted at the
septum and assumes a spherical shape, at length only attached by a short
narrow neck. Beneath this again the same process is repeated to form
another and another conidium in succession, until a bead-like string of
conidia surmount each of the tubes from which they are produced (Plate
X. fig. 200). At length the distended epidermis above is no longer able
to bear the pressure of the mass of engendered conidia within, and is
ruptured irregularly, so that the conidia, easily separating from each
other at the narrow neck, make their escape.

As long since as 1807, M. Prevost described the zoospores, or moving
spores, of these conidia, and his observations were confirmed by Dr. de
Bary three years since, and are now adverted to by him again in further
confirmation. If the conidia (white spherical bodies ejected from the
pustules of the “white rust”) are sown in a drop of water on a glass
slide, being careful to immerse them entirely, they will rapidly absorb
the water and swell; soon afterwards a large and obtuse papilla,
resembling the neck of a bottle, is produced at one of the extremities.
At first vacuoles are formed in the contents of each conidium; as these
disappear, the whole protoplasm (granular substance filling the
conidium) becomes separated by very fine lines of demarcation, into from
five to eight polyhedric portions, each with a faintly coloured vacuole
in the centre. These portions are so many _zoospores_. Some minutes
after the internal division, the papilla swells and makes itself an
opening, through which the zoospores are expelled one by one, without
giving any signs of movement of their own. They take a flat disk-like or
lenticular form, and group themselves about the opening, whence they
have been expelled, in a globular mass. Soon, however, they begin to
move, vibratile ciliæ show themselves, and by means of these appendages
the entire globule oscillates, the zoospores disengage themselves from
each other, the mass is broken up, and each zoospore swims off on its
own account (Plate X. fig. 208).

The free zoospores are of the form of a planoconvex lens, obtuse at the
edge. Beneath the plane face, out of the centre, and towards that point
of the margin which during the movement of the zoospore is foremost, is
a disk-shaped vacuole, with two ciliæ of unequal length attached to its
margin; the shorter cilia is directed forwards, and the longer in the
opposite direction, during the evolutions of the zoospores.

The zoospores are produced within from an hour and a half to three hours
after the sowing of the conidia in water. They are never absent if the
conidia are fresh, or even a month old, but beyond this period their
artificial generation is very uncertain. This little experiment is a
very simple and interesting one, and may be performed by any one who
will take the trouble to follow out these instructions.

From this simple experiment, let us turn for a moment to the plant in
its natural condition when affected by the white rust. If, after rain or
dew, when the little drops of moisture hang like pearls about the sickly
pallid leaves of the shepherd’s-purse, bespattered with the white
pustules of the rust, we collect and examine a drop of water from the
immediate neighbourhood of one of the pustules, we shall commonly find
empty conidia and zoospores in different stages of development.


[Illustration:

  Plate XI.
  W. West imp.
]


Water alone seems to be essential to them, and for this the conidia may
remain unchanged for a month, and literally burst into activity at the
first gentle shower, till the whole surface of the plant is swarming
with zoospores. We may no longer doubt that a true vegetable produces
from itself bodies endowed with active motion, resembling low forms of
animal life, and yet in themselves not animalcules, as some would
suggest, but essentially vegetable, as we shall hereafter demonstrate.
To scientific men this is not new, except as regards fungi, for in algæ
such bodies have long been recognized.

A second kind of reproductive organs are described by Dr. de Bary; and
if future examinations confirm his observations, as they doubtless will,
this feature is an important one. It is true that M. Caspary long since
detected similar bodies in moulds (allied to that which produces the
potato disease), but he only knew _them_ in a limited sense compared
with what De Bary has revealed. These fruits are hidden amid the tissues
of the plant on which the “white rust” is parasitic, and only betray
their presence by the coloration of those tissues. To these bodies it is
proposed to give the name of “oogonia” and “antheridia,” on account of
their presumed sexuality, the “oogonia” representing the female, and the
“antheridia” the male organs.

The oogonia are large spherical or ovoid cells, with a thickish membrane
containing a granular protoplasm, or formative fluid. They are produced
either terminally or laterally upon the threads of the mycelium, from
which they are separated by septa or partitions.

The antheridia are somewhat blunt-shaped or obovate cellules,
considerably smaller than the oogonia, with slightly thickened walls,
and containing a finely granular protoplasm. These are produced upon
branches of the mycelium which do not bear oogonia. The obtuse
extremities of these branches, which are to be developed as antheridia,
are applied to the surface of the growing oogonia, to which they adhere,
become distended, assume their obovate form, and by the formation of a
septum at their base, their contents are isolated from those of the
threads of the mycelium, and thus the antheridia are perfected.

When these bodies have attained their full dimensions, the large
granules which are contained in the oogonium accumulate at its centre,
and form an irregular, somewhat spherical mass, which is called by De
Bary a _gonosphere_. This gonosphere having been formed, a straight tube
shoots out from the antheridium which perforates the wall of the
oogonium, passes through the fluid which surrounds the gonosphere,
elongating itself until it touches that body. From this period a
membrane begins to be formed about the gonosphere, which thenceforth
maintains a regular spheroidal form. It may be observed that the
extremity of the tube which proceeds from the antheridium does not open,
and the fecundation, if such it be, is produced solely by contact. After
this contact of the two bodies, the gonosphere acquires a new name, and
is called an “oospore.” The membrane which at first invests this organ
is very thin, but by deposits from the surrounding fluid it attains to a
greater thickness, and is at length of a yellowish-brown colour, having
its surface studded with large obtuse warts (Plate X. fig. 206). One of
these warts, larger than the rest, forms a kind of thick sheath around
the fecundating tube.

The oospores do not give evidence of any appreciable change for some
months. For instance, those collected by De Bary in June did not attain
their ulterior development until the commencement of December. The
method adopted was as follows:—Parts of the plants containing ripe
oospores were preserved in the dried state. When examination was
considered desirable, the portion to be employed was immersed in water
for a day or two; it was then placed on a humid soil, or mould covered
with blotting-paper. The tissues enclosing the oospores were decomposed,
and at the end of from four to eight days their germination might be
observed when placed in a drop of water. This method again corresponds
with the ordinary processes by which the plant naturally decays on
exposure to the influences of the atmosphere, and the oospores germinate
under the favour of a shower of rain.

If the oospore, after the decay of the tissues, is isolated and placed
in a drop of water, the brown investing membrane will be seen to rupture
irregularly, and its contents (enclosed in a transparent inner membrane)
issuing from the orifice. As in the case of the conidia, this body at
first contains vacuoles, and is afterwards divided into polyhedric
portions; these pass into zoospores, which congregate at the centre into
a globular mass (Plate X. fig. 207). They afterwards separate, and for
some minutes float about in the vesicle in which they were generated.
Ultimately the membrane ruptures, and the zoospores swim about in water
just as those produced from the conidia had done. The number contained
in each oospore is considerable, and may be estimated at not less than
one hundred.

The zoospores, whether produced from conidia or from oospores, appear to
be the same. The movements of both in the water last from two to three
hours; then they cease, the ciliæ disappear, and the zoospores remain at
rest, taking meanwhile a globular form. Afterwards these spores (for
having ceased all motion they are no longer zoospores) emit a thin tube
from some portion of their surface, such tube attaining a length of from
two to ten times that of the spore whence it proceeds. The extremity of
these tubes swells and forms a kind of cell, into which the contents of
the spore pass through the medium of the tube (Plate X. fig. 209).

Thus far, and thus far only, has Dr. de Bary been enabled to trace the
development of the zoospores in a drop of water. Another series of
experiments was instituted by this mycologist having especial reference
to the parasitism of the “white rust.” He made numerous observations to
ascertain whether the spores, or the germinating tubes, entered by the
roots of growing plants, and satisfied himself that they did not. Plants
of garden-cress, mustard, and shepherd’s-purse had their roots immersed
in water impregnated with zoospores. After one or two days, though the
surfaces of the roots were covered with zoospores that had emitted their
germinating tubes in all directions, none had penetrated or showed the
least tendency to penetrate the epidermis. Other plants were planted in
flowerpots and watered at the roots with water charged with zoospores,
and for two days the pots were left standing in the water similarly
charged, then the plants were removed, cultivated in the ordinary
manner, grew up healthy, and gave no signs of the white rust. Care had
been taken that neither stems nor leaves should come in contact with
water containing zoospores.

If a drop of water thus charged is placed on the surface of a living
leaf of the shepherd’s-purse, for instance, and left at rest for a few
hours and examined minutely at the end of that period, they will be
found to have germinated. Let the epidermis be removed carefully and
placed on a glass slide and submitted to the microscope. Many zoospores
will be found to have produced from that point of their surface which is
nearest to one of the stomata, or pores of the leaf, its slender tube,
and to have thrust it through those openings, with the swollen extremity
resting in the air-cavity situated beneath the pore. If many days, or
even weeks, are allowed to pass, and the leaf is examined again, or
another leaf similarly treated, and kept in a living and vigorous
condition by remaining attached to the parent plant, still no further
change or advance will be observed, the germs will appear fresh, and
still in the same condition. Hence it is concluded that plants are not
infected through the medium of their leaves.

If the cotyledons, or seed-leaves, are watered with similar impregnated
water, a different result has been observed to take place. The
germination of the tubes till their entrance at the stomata is the same;
but, having entered, the swollen extremity elongates, becomes branched,
and takes all the appearance of mycelium such as we at first described.
If the infected plant endures through the winter, the mycelium endures
with it, to recommence vegetating in the spring.

The experiments which Dr. de Bary performed were all upon plants of the
common garden-cress. It will be unnecessary to repeat all the details of
these, as given in the memoir recently published on the subject, but it
will suffice to give a summary of results. In two series of plants
cultivated at different periods from good seeds, one hundred and five
plants which, had not received the water impregnated with zoospores upon
their cotyledons vegetated without any indications of the parasite.
Amongst the eighteen plants which were inoculated by watering the
cotyledons, four only were not attacked by the parasite, fourteen bore
the “white rust.” In six of these it did not extend beyond the
cotyledons; in the others it also appeared on the stems and leaves.

From these experiments it may be deduced that plants are not infected by
spores of the parasite entering at the roots, or by their leaves, but
that inoculation takes place through the medium of the cotyledons, or
seed-leaves; that the agents in this inoculation are the zoospores
produced either from the conidia or the oospores; that they do not enter
the stomata or pores themselves, but thrust out a germinating tube, into
the extremity of which the contents of the zoospores pass; that when
these tubes have entered the stomata of the cotyledons they branch and
ramify, becoming a true mycelium, from which fruitful parasites are
developed; that if a plant so infested lives through the winter, the
parasite lives with it, to vegetate again in the spring.

The immense number of zoospores capable of being produced from a single
infested plant is almost beyond calculation. It is easy for a million of
conidia to be developed from such a plant, each producing from five to
eight zoospores, besides a large number of oospores, each containing a
hundred zoospores. It can scarcely be considered marvellous that the
white rust should be so common on plants favourable to its development,
the marvel being rather that any plant should escape.


[Illustration:

  Plate XII.
  W. West imp.
]


Until recently it was doubtful whether more than one or two species of
_Cystopus_ (white rust) were known. It is now certain that we have three
in Great Britain, and three or four others are found elsewhere. Of the
British species one is found on many cruciferous plants, as the
shepherd’s-purse, garden-cress, mustard, radish, and plants of the
cabbage kind. This is the _Cystopus candidus_. Another occurs on the
goat’s-beard, salsify, and scorzonera, which is called _Cystopus
cubicus_. Both have great external resemblances, but both possess
specific internal differences. In the Goat’s-beard rust (Plate X. fig.
201) the terminal conidia in the bunches or fascicles of conidia which
are produced within the pustules are spheroidal, large, and of a
yellow-brown tint, whilst the residue are cylindrical, smaller (Plate X.
fig. 202), and more or less compressed. In the crucifer rust the conidia
are all equal in the pustules and globose. The oospores in the former of
these are subglobose and the warts on their surface are solid; whilst in
the latter the oospores are truly globose, and the warts on the surface
are hollow (Plate X. fig. 210). The third species is the Sandspurry
white rust (_Cystopus Lepigoni_), which was found on the common
sandspurry (_Spergularia rubra_) by Mr. R. G. Keeley, in Swanscombe
Marshes (September, 1864). Of the other species it is not improbable
that one or two may yet be found in this country. Without attempting to
indicate their microscopic differences, it may be serviceable to name
the species of phanerogamic plants on which they are likely to be found.
The Purslane white rust (_Cystopus Portulacæ_, D. C.) should be sought
on the purslane, which, though of limited cultivation, is exceedingly
liable to attack from this parasite, and the Thistle white rust
(_Cystopus spinulosus_, D. By.) may probably be met with on the leaves
of the common thistle (_Cnicus arvensis_) or some of its allies.

Considerable interest is now attached to these parasites, which, as far
as we at present know, differ materially in their reproduction from the
other dust-like or uredinous fungi with which they have long been
associated. Dr. de Bary proposes the union of these with the mould-like
fungi of the genus _Peronospora_, to which the mould infesting the
potato belongs, so as to constitute by themselves a group apart from the
genera with which both have heretofore been associated. Whether his
views will be accepted by mycologists time will speedily prove. Under
any circumstances, microscopical and botanical science will reap
considerable benefit from his researches.


------------------------------------------------------------------------



                              CHAPTER XI.

                               _MOULDS._


TWENTY years since, and some of these little pests were altogether
unknown, whilst others were only recognized and partly understood by a
few scientific men. During the period to which we have alluded more than
half the present species contained in the genus _Peronospora_ had never
been observed, and amongst these the most devastating of its tribe, the
associate and undoubted cause of the potato disease.

Parasitic fungi are far more numerous, both in individuals and species,
than most persons are aware, and cultivated plants of all kinds are more
or less subject to their ravages. Some are more susceptible than others,
of which the corn and grass tribe, or _Graminaceæ_, as they are termed
by botanists, is an example. Not less than thirty species have been
recorded upon plants of this natural order, and of these nearly one-half
are found upon the living plants. Upon the potato plant, again, no less
than ten different kinds of fungi have been described; whilst upon other
and more fortunate plants only one or two parasites of this nature
establish themselves.


                              Plate XIII.

[Illustration:

  262.—TURNIP MOULD.
  _Peronospora parasitica._
]

[Illustration:

  263.—ONION MOULD.
  _Peronospora Schleideniana._
]


It will be sufficient for our present purpose to state that one of the
six families into which fungi are divided for scientific purposes is
called _Hyphomycetes_, a name compounded of two Greek words signifying
“thread” and “mould,” or “fungus,” and is applied to this group because
the thread-like filaments of which they are largely composed are the
most prominent feature. In this family there are again a number of
smaller groups called orders, having an equal value to the natural
orders of flowering plants; and one of these orders, called _Mucedines_,
has the fertile threads perfectly distinct from the mycelium or spawn.
These threads are sometimes simple and sometimes branched; they may be
articulated or without articulations or septa, short or long, erect or
creeping, hyaline or whitish, mostly free from colour, and are not
coated with a distinct membrane. The spores are generally simple,
sometimes solitary, at others in pairs, or strung together like beads
for a necklace. Amongst all this variety of arrangement there is order,
for these are but features, or partly the features, of the different
genera of which the _Mucedines_ are composed. One of the genera is
termed _Peronospora_, and to this the parasitic fungus of the potato,
and some others to which we shall have occasion to refer, belong. In
this genus the threads are generally branched, but without
articulations. The spores, or seed-like bodies, are of two kinds; one
kind is borne on the tips of the branches; and the other kind, which is
larger and globose, is borne upon the creeping mycelium or spawn. All
the members of this genus with which we are acquainted are parasitic on
living plants, inducing in them speedy decay, but preceding that decay
of which they are themselves the cause. Hence we have deemed it the more
advantageous course both for writer and reader to associate together the
different species of this particular genus of parasitic moulds in one
chapter, rather than bring together the different kinds of fungi,
belonging perhaps to widely separated genera, but all associated with,
or parasitic upon, the same plant. The botanical student will thank us
for following this plan, and the general reader will labour under no
disadvantage, in this instance at least, from the similarity of the
diseases produced in the plants infested.

It has been recently proposed to associate the genera _Peronospora_ and
_Cystopus_ together in one group, under the name of _Peronosporei_; but
with the discussion of this subject we have nothing to do in this
volume. Having announced this fact, we shall continue to notice them in
the several positions heretofore accorded to them.

The mycelium (root-like fibres) in this genus greatly resembles that
described for the “white rusts,” though neither so thick, nor is the
membrane so gelatinous as in that genus. In some instances the mycelium
is confined to the inter-cellulary passages; but in most cases they also
perforate the cells of the plant which nourishes them. The sucker-like
bodies already described in _Cystopus_ are often found produced on the
mycelium of _Peronospora_, but occasionally they appear to be absent,
especially in the mould causing the potato disease.

From the mycelium erect threads are produced, upon which one form of
fruit, which may be termed “acrospores,” is borne. These filaments are
sometimes single, and sometimes in small tufts or fascicles. In some
instances they are considerably branched, so as to present a dendroidal
or tree-like appearance; in others they are nearly simple, being only
surmounted by short spicules; or, in one instance, quite simple, and
only surmounted by a single acrospore. The branching habit is by far the
most common.

Each ultimate branch in the ramification of the fertile filaments
engenders a single acrospore. Its extremity, at first thin and pointed,
swells in the form of a globular vesicle, which soon takes the
elliptical or ovate shape of the perfected acrospore, and at length
separates itself from the branch that supports it.

In all instances the acrospores have a similar structure, but with
minute differences in form, &c., which have their importance in the
determination of species. In most cases the apex of the acrospore is
obtuse, and the entire body has a violet tint, more or less deep; in
some it is completely colourless. These acrospores, when placed in
favourable conditions, will germinate, and, in fact, comport themselves
in the manner of true spores.

During the year 1861, Dr. de Bary published an account[8] of the
discovery by him of zoospores, similar to those already described in
connection with the conidia of the “white rusts,” produced from the
acrospores of the mould which originates the potato disease. In the same
author’s memoir of 1864, already quoted, the observations there made are
confirmed. When the acrospores of the potato mould and the parsnip mould
are sown in water upon a glass slide, their contents become divided, and
vacuoles are formed, as already described in _Cystopus_; these parts are
expelled through an apical orifice, and, when free, take the form of
perfect zoospores, and commence swimming about in the fluid surrounding
them.

Footnote 8:

  Die gegenwartig herrschende Kartoffelkrankheit, ihre Ursache und ihre
  Verhütung. Von Dr. A. de Bary. Leipsig: 1861.

These zoospores are oval, or semi-oval, with a structure resembling that
of the “white rusts,” save that the two ciliæ, or vibratile hairs,
proceed from the same point. The number of zoospores from each acrospore
of the potato mould is stated to be from six to sixteen, and in the
parsnip mould from six to fourteen. Their ultimate development is the
same as has already been described. In the potato mould, the production
of the zoospores is much favoured by the exclusion of light.

Another mode of germination in the acrospores of the potato mould has
been observed by the same eminent mycologist. This results when the
spores are sown upon a humid body, or on the _surface_ of a drop of
water. The acrospore emits from its summit a simple tube, the extremity
of which swells into an oval vesicle; into this the contents pass, and
it isolates itself by a partition from the germ-tube. Thus it becomes a
duplicate of the acrospore from whence it was derived. This secondary
body has also the power of producing a tertiary cellule in a similar
manner. Both the second and third cellule, when _immersed_ in water,
produce zoospores in the ordinary manner, as above described.

Yet another and a third mode of germination is described by the same
author, in which the acrospore emits from its apex a germ-tube, which
elongates considerably; and into this long and tortuous tube the
contents of the acrospore pass, and accumulate at the opposite
extremity.

The germ-tubes, produced in the manner last described, when developed on
the surface of a favourable plant, perforate the cells of the epidermis,
or enter by the stomata. In the case of the potato mould, the germ-tubes
enter by the stomata; but in the majority of species the germ-tubes do
not enter by the natural pores of the leaves upon which the acrospores
are sown, but perforate the cellules, and thus effect admission into the
tissues of the plant, where they extend, ramify themselves, and become a
mycelium. This mycelium originates branched threads, bearing acrospores
at the tips of their branchlets, and in many species of _Peronospora_
another kind of reproductive body upon the threads of the mycelium
itself. To these bodies we must briefly address ourselves.

This last kind of reproductive organs (not yet positively found in the
potato mould) appear to be wholly analogous to the oogonia of the “white
rusts” already described, producing oospores in like manner. Dr. de Bary
avows with regret that his numerous efforts to observe the germination
of these oospores were unsuccessful. Nevertheless, he considers that the
perfect resemblance between them and the oospores of the “white rusts”
will justify him in concluding that the germination in both is very
similar. It will be unnecessary to repeat here the observations already
made on the growth and development of oogones and zoospores. What has
been advanced respecting these organs in _Cystopus_ will apply also to
_Peronospora_.


                               Plate XIV.

[Illustration:

  264.—POTATO MOULD.
  _Peronospora infestans._
]

[Illustration:

  265.—LETTUCE MOULD.
  _Peronospora gangliformis._
]


POTATO MOULD.—Towards the close of the summer of 1845, in the course of
a few weeks, every one became aware of the fact that a new disease had
appeared which threatened the entire destruction of the potato crop.
Until then it seemed to have been almost, although not entirely unknown.
It first appeared in the Isle of Wight about the middle of August, and a
week afterwards had become general in the South of England, and the next
week there were but few sound samples of potatoes in the London market.
Early in September the disease had commenced its ravages in Ireland, and
shortly afterwards it was discovered in Scotland. With the same rapidity
it seems to have spread throughout Europe and North America, or at least
the western portion of the former and the northern districts of the
latter. It must not be imagined, however, that the Isle of Wight was the
centre from which this disease spread over such an extended area and
with such alarming rapidity. From this spot it doubtless made its first
appearance that year amongst our own crops, but there is not the least
doubt of its existence both on the continent of Europe and in North
America in the previous year, and the farmers of Belgium had noted its
appearance in the province of Liège as far back as 1842 and 1843. Other
diseases had been observed affecting the potato crop before, and one
which was also associated with a parasitic fungus had made its
appearance in 1815. It is also exceedingly probable that, in a milder
form, the murrain was present with us a year or two before it broke out
to such an alarming extent. A correspondent to the _Gardeners’
Chronicle_, in 1844, notices it in the Isle of Thanet, and another
testifies to its occurrence in districts of Ireland for two or three
years previous to its general outbreak. The description of the disease
in Canada, in 1844, contained in a letter addressed to Dr. Bellingham,
and quoted by the Rev. M. J. Berkeley,[9] leaves no doubt of its
identity:—“During the months of July and August (1844), we had repeated
and heavy showers, with oppressive heat, and an atmosphere strongly
charged with electricity. Towards the close of the month of August I
observed the leaves to be marked with black spots, as if ink had been
sprinkled over them. They began to wither, emitting a peculiar,
offensive odour; and before a fortnight the field, which had been
singularly luxuriant, and almost rank, became arid and dried up, as if
by a severe frost. I had the potatoes dug out during the month of
September, when about two-thirds were either positively rotten,
partially decayed and swarming with worms, or spotted with
brownish-coloured patches, resembling flesh that had been frost-bitten.
These parts were soft to the touch, and upon the decayed potatoes I
observed a whitish substance like mould.”

Footnote 9:

  Journal of Horticultural Society of London, vol. i. p. 11.

Although this disease made its first appearance, in the middle of
August, 1845, in the Isle of Wight, it had already appeared in Belgium
in the same year, a month previously; and although it may have been
noticed in other British localities in 1844, it was known in Canada and
in St. Helena in the same year to a far greater extent, and in Liège as
early as 1842. There are, therefore, good grounds for believing that the
European centre was Belgium; but if M. Boussingault was correct in
stating that “this malady is well known in rainy years at Bogota, where
the Indians live almost entirely on potatoes,” then it is not of
European but American origin, and is probably derived from districts not
far remote from those whence Europe first received the potato itself.

It would occupy too much space to detail the different theories and
opinions relative to the causes of this disease to which 1845 and
subsequent years gave birth. Suffice it to say, that the lapse of years
has silently proved the majority of these to have been fallacious. All
such as imputed to peculiar electric conditions, a wet season, or other
meteorological influences, the disease which has re-appeared under
different conditions and influences, and in seasons remarkable for
dryness, are manifestly refuted; whilst its mycological origin has
continued to gain adherents, and the gradual accumulation of fresh facts
has almost placed it beyond dispute not only that the potato disease is
accompanied by, but results from, fungal growth. Unfortunately, this
disease has been so prevalent, more or less, during the past eighteen
years, that few have been without the opportunity of making themselves
acquainted with its external appearance. To this may be added the minute
and exact account of its development, as recorded by that excellent
mycologist and careful observer, the Rev. M. J. Berkeley, in 1846, and
to which, even now, nothing of importance can be supplemented or
abstracted:—“The leaves began suddenly to assume a paler, and at length
a yellowish tint, exhibiting here and there discoloured spots. More or
less coinciding with these spots, on the reverse of the leaves, appeared
white mealy patches, consisting of a minute mould, proceeding, either
singly or in fascicles, from the stomata, and arising from an abundant
branched mycelium creeping in every direction through the loose tissue
beneath the cuticle. The upper surface rarely, if ever, exhibits the
mould, it being almost physically impossible for its delicate threads to
penetrate the closely-packed cells which, being arranged side by side,
leave scarcely any intercellular passages. The mould, in a few hours
from its first piercing the apertures of the stomata, perfects its
fruit, and in so doing completely exhausts the matrix, which in
consequence withers. No sooner have a number of the leaves been
attacked, than the stem itself is subject to change, becoming spotted
here and there with dark brown patches, in which the cells are mostly
filled with a dark grumous mass, without exhibiting any mucedinous
filaments; though, occasionally, I have ascertained their presence. Very
rarely fructifying but dwarfed specimens of the mould occur upon it. The
stem now rapidly putrefies, the cuticle and its subjacent tissue become
pulpy, and separate when touched from the woody parts beneath. The whole
soon dries up, and in many instances exhibits in the centre the black,
irregular fungoid masses which are known under the name of _Sclerotium
varium_, and which are believed to be the mycelium of certain moulds in
a high state of condensation.

“If the tubers are now examined, the greater part will often be found
smaller than usual, especially if the disease has commenced at an early
stage of growth; but in their natural condition, while here and there a
tuber, particularly if it has been partially exposed, exhibits traces of
disease. The surface is, however, soon marked with livid patches,
commencing generally about the eyes, or at the point of connection with
the fructifying shoots: these rapidly acquire a spotted appearance, the
spots being rather waved, and assuming often a more or less concentric
arrangement. Sometimes—especially on the smoother kinds of tuber—two or
more regular systems of concentric spots are exhibited on the same
tuber. The skin now withers, and is easily separated; the spots become
depressed and of a yellowish tinge; and if the tubers be laid in a moist
place, in a day or two—sometimes in a few hours—the same mould which
destroyed the leaves springs from them, piercing the cuticle from
within, yet not scattered, as on the leaves, but forming a conspicuous
white tuft. If a section of the diseased tuber be made on the first
symptoms of the disease, little brownish or rusty specks are found in
the cellular tissue, confined, with very rare exceptions, to the space
between the cuticle and the sac, if I may so call it, of spiral vessels
and their accompanying tissue, which, springing from the subterranean
branches, pass into the tuber, making their way to the several buds
disposed on the surface. These spots consist at first of a quantity of
discoloured cells, mixed more or less with others in a healthy
condition. The grains of fecula are for a long time perfectly healthy;
the cells themselves, so far from being looser, are more closely bound
together than in the more healthy portions. The rusty spots soon exhibit
a darker tint, spreading in every direction and becoming confluent; they
at length extend beyond the barrier of vascular tissue, and attack the
central mass. The tuber, meanwhile, assumes a disagreeable smell,
decomposes more or less rapidly, other Fungi establish themselves on the
surface, or in the decaying mass, which emits a highly fetid odour,
resembling that of decaying agarics; the union of the cells is
dissolved, animalcules or mites make their appearance, till at last the
whole becomes a loathsome mass of putrescence.”

The form of the mould itself is represented (fig. 264) as exhibited
under the microscope, with the nodose swellings of the branches, and
spores attached to the tips. These acrospores are filled with a granular
mass, from which, as hereafter described, zoospores are produced. The
branching dendroidal threads of this fungus proceed from a creeping
mycelium or spawn of entangled filaments which interpenetrates the
matrix, upon which it establishes itself. Upon these threads spherical
bodies were long since observed by Dr. Payen, and, under the name of
_Artotrogus_, described by Dr. Montagne as a new species of fungus. Dr.
de Bary failed to detect oospores on the mycelium of this mould,
although the organs found by Payen in some sort resemble them. De Bary
sought in vain, also, for the spherical bodies described by the author
above named. It has been calculated that one square line of the under
surface of the leaves is capable of producing 3,270 acrospores, each of
which yields at least six zoospores, sometimes double that number; thus
we have 19,620 reproductive bodies from that small space. The mycelium
from the zoospores is capable of penetrating the cellular tissue in
twelve hours, and, when established there, it bursts through the stomata
of the leaves, and fruit is perfected in from fifteen to eighteen hours.
Since the zoospores are perfected and ready to germinate in twenty-four
hours from their being placed in water, it becomes almost impossible to
calculate the myriads of fungi that may be produced from a single
centre. Dr. de Bary has also demonstrated that the brown spots so
characteristic of the disease are the result of the action of the spores
or zoospores. By placing a quantity of spores in a drop of water on the
leaves, stems, and tubers under a glass sufficiently air-tight to
prevent evaporation, he produced the brown spots, and traced their
progress from the earliest stages.

There are a few practical conclusions which may be drawn from these
discoveries. In the first place, it is clearly shown by the production
of the spots that the fungus is capable of _causing_ the disease, a fact
which has been disputed, but now placed beyond doubt. The inference is,
that not only is it capable of producing, but is really the cause of the
potato murrain. With bodies so minute and active as the zoospores, there
can no longer be difficulty in accounting for their penetrating the
tissues of the plant. They are most active and productive in wet
weather, especially when it is also warm. Moisture appears to be
essential, and a dry season the greatest enemy to the spread of the
disease. That bodies so minute and subtle should have baffled all
efforts to destroy or eradicate, is not now surprising. Whether any
method will be found to contend successfully with it, is now more
doubtful than ever. A careful reperusal of the old facts by the aid of
this new light will tend to the elucidation of much of the mystery in
which the subject has been involved. All who have hitherto been
sceptical of the mycological source of one of the greatest pests of
modern times should study M. de Bary’s pamphlet.


                               Plate XV.

[Illustration:

  266.—PEA MOULD.
  _Peronospora Viciæ._
]

[Illustration:

  267.—ANEMONE MOULD.
  _Peronospora pygmæa._
]


The potato mould has been judiciously named _Peronospora infestans_, or,
as it was at first called, _Botrytis infestans_; but on a revision of
the genera _Botrytis_ and _Peronospora_, it was transferred to the
latter genus, in which it remains. Three names were given to it, within
a short period of each other, by different mycologists, in ignorance of
its having already received a name. The one we have adopted appears to
have the priority, at least of publication, and was given by Dr.
Montagne. That of _Botrytis devastatrix_ was given by Madame Libert, and
_Botrytis fallax_ by M. Desmazières. The principal feature in this
species seems to consist in the branches becoming alternately thickened
and constricted, so as to resemble a moniliform string or necklace of
little bladders or vesicles. The branches are also more erect than in
the allied species, and the spores are solitary on the tips or from the
sides of the branches, and not in pairs or clusters, and the tips are
simple, and not bifid or trifid, as in most of its allies. It need
scarcely be remarked, that a high power of the microscope is necessary
to make out the distinctive features of the different members of this
genus, and that to the naked eye they only appear as a minute whitish
mould. As already stated, this little fungus makes its first appearance
on the under surface of the leaves, especially the lower ones, of the
potato plant, and afterwards attacks the stem, and ultimately the tuber.
For examination it is better to select the leaves soon after the fungus
makes its appearance.

TURNIP MOULD.—Since the advent of the potato murrain a similar disease
has been witnessed, though more limited in its extent, amongst Swedish
turnips, commencing in little waved irregular lines following the course
of the vessels, around which spots are formed by the deposition of dark
granules in the same manner as in the potato. In this instance, the
leaves apparently are first attacked in a similar manner by a species of
mould or _Peronospora_ allied to the one already described, but which
has been long known as parasitic upon cruciferous plants, to which the
turnip belongs. This species, termed _Peronospora parasitica_, is white
in all stages of its growth. It is much more branched, and the branches
are comparatively shorter than in the potato mould, and the tips of the
branches are bifid (fig. 262). The acrospores are very large and
globose, features also which distinguish this mould from the last. A
short time since we were called to witness a bed of splendid
cauliflowers, which had, up to that time, been the pride of their
cultivator; but, alas! their glory was threatened with speedy
annihilation, for in nearly every instance the lower leaves had become
more or less covered on their upper surface with yellow spots, and
beneath glaucous with the mould we have been describing. The diseased
leaves were all immediately removed, but we fear without success,
although no positive information has since reached us. The almost
unnatural vigorous green of the leaves, prior to the appearance of the
mould, is not at all an uncommon occurrence: this phenomenon has been
noticed in the ears of corn, in which every grain was soon afterwards
filled with spores of bunt.

This species was at one time believed to be parasitic on the “white
rust,” from which circumstance its specific name was derived. More
precise examination proves that it sometimes occurs where no white rust
is present, and therefore its parasitism is imaginary. The suckers in
this species are large and penetrate the cells, often entirely filling
them. This feature is sufficient to distinguish the mycelium of the
mould from that of the “rust.” The turnip mould occurs on many
cruciferous plants, and especially on the shepherd’s-purse, as well as
upon the different varieties of cabbage and its more immediate allies.

ONION MOULD.—Another disease, produced by fungi of the same genus, makes
its appearance upon young onion plants in the spring. The mould is
called _Peronospora Schleideniana_, and has many features in common with
those already described. In this instance the threads are greyish and
erect, with alternate branches, not divided by transverse septa, and the
spores are obovate, attenuated towards their base (fig. 263). This
mould, in some years, is very common and destructive, by preventing the
young plants which are attacked from coming to perfection. It is not
confined to the onion, but appears on other allied species of _Allium_
(to which the onion belongs). The threads form large patches or blotches
on the leaves, and sometimes cover them entirely. It very much resembles
the turnip mould, from which the form of the spores considerably
differs. This is the same species as that described by Caspary, and
afterwards by Berkeley, under the name of _P. destructor_.

_Lettuce Mould._—A very similar mould (_Peronospora gangliformis_) is
sometimes very common in spring on the under surface of the leaves of
the cultivated lettuce, appearing in definite white mouldy spots. By
reference to the figure of a portion of a thread magnified (fig. 265),
it will be seen that the peculiar form of the tips of the branchlets
evidences the distinctness of this species.

The oospores are small, globose, and of a yellowish-tawny colour. This
mould is by no means confined to lettuces, but has also been found on
species of ragwort, sow-thistle, nipplewort, endive, and other composite
plants; and has from time to time received numerous names, which it is
unnecessary to enumerate.

TARE MOULD.—The under surface of the leaves of tares, and sometimes also
of peas, is liable to attack from an allied species of mould
(_Peronospora Viciæ_). In the spring of 1846 it appeared amongst vetches
in some districts to such an extent as at one time to threaten the
destruction of the crops; but a succession of dry weather at once
abridged its power and limited its mischief. Mouldy vetches and mouldy
peas are, especially in moist seasons, evils to which the agriculturist
knows his crops to be subject; he may not know, however, that this kind
of mould (fig. 266) is of so near a kin to that which has acquired such
wide-spread fame in connection with the potato. Another species of
fungus attacks the garden pea in damp seasons, forming small depressed
brownish spots on the leaves and pods; but this is quite distinct from
the mould, though probably not less injurious.

The fertile threads are produced in dense clusters, each many times
branched, and bearing elliptic acrospores obtuse at their apices, and of
a violaceous tint (fig. 266). The oospores are beautifully reticulated
and of a yellowish-brown colour (Plate X. fig. 212).

Trefoil and some other allied plants are attacked by another species,
characterized by Dr. de Bary as _Peronospora trifoliorum_, which we have
found rather plentifully in some localities on lucern.

THE PARSNIP MOULD (_Peronospora nivea_, Ung.) is found on many
umbelliferous plants; but its attacks upon the parsnip are most to be
deplored, because it injures and ultimately destroys an article of human
food. The plants infested with this parasite are first attacked in the
leaves, but afterwards the roots become spotted and diseased in a
similar manner to the potatoes attacked by its congener. The disease has
not hitherto been so general with the former as the latter; but in some
districts it has been far from uncommon.

The fertile threads are collected in bundles, erect, and not so much
branched as in many other species. The acrospores are subglobose or
ovoid, and papillate at their apices. This species is sometimes called
_P. umbelliferarum_, and sometimes _P. macrospora_. Generally speaking
the average humidity of a season but little affects the production of
parasitic fungi. In a dry season, like that of 1864, we found as many
species, and these as flourishing and numerous in individuals, as in a
proverbially wet year. Such is not the case, however, with the moulds
under notice, or such fungi as are reproduced through the medium of
zoospores: these are undoubtedly less common in a very dry season; but
it must be remembered that a single shower is sufficient for the
development of zoospores, and occasional showers or heavy dews will
speed them on their course of destruction as readily almost as
continuous moisture. The large fungi, on the contrary, become very
limited in numbers when the weather is unusually dry.

SPINACH MOULD.—Spinach is likewise liable to suffer from the
establishment of a mould upon the under surface of the leaves:
unfortunately this is not unfrequent, and has been known in England
certainly for the last fifty or sixty years, since it was figured by
Sowerby in his “British Fungi” as many years since. We have lately seen
a bed of spinach, utterly destroyed by this fungus; whilst on another,
not twenty yards apart, not a spotted leaf could be found. This mould is
the _Peronospora effusa_ of botanists; it occurs also on some species of
goosefoot (Plate X. fig. 215), and probably on knotgrass. To the naked
eye it appears in pale purplish-grey patches, which, when examined
microscopically, are found to consist of dense bundles of branched
threads, bearing ellipsoid acrospores, the membranes of which have a
violaceous tint. The oogonia produced upon the mycelium vary
considerably in size. The oospores are of the character delineated in
our plate (Plate X. fig. 214).

Hitherto all the species of mould to which we have had occasion to refer
have been found infesting plants more or less employed as food; but
there remain one or two other species to which we must make special
reference. One of these affects the most universal of favourites amongst
flowers: this is the rose mould. Attention was directed to this mould,
and it was described for the first time under the name of _Peronospora
sparsa_, in the columns of the _Gardeners’ Chronicle_, in 1862. It
occurred on a quantity of potted rose-plants in a conservatory.
Irregular pale brownish discoloured spots appeared on the upper surface
of the leaves; these extended rapidly, and in a short time the leaves
withered and shrivelled up, and ultimately the whole plant perished. A
delicate greyish mould was to be seen by the aid of a lens, scattered
over the under surface of the leaves. By the microscope, the branched
threads, having the tips furnished with subelliptic spores, were
revealed, and an ally of the potato mould found revelling amongst the
roses.

During the winter of 1863-4, we found the leaves of several species of
dock occupied by a mould which appears to be a very low form of
_Peronospora_. Its presence was indicated by brownish orbicular spots,
on which the fertile threads occurred in small bundles. These threads
were generally simple, but occasionally forked, bearing rather large
elliptical acrospores _attached obliquely_ to the tips of the threads
(fig. 269). In consequence of this peculiarity, we have named the
species, which does not appear to have been noticed before, _Peronospora
obliqua_. It is clearly very distinct from another species found on dock
leaves by Corda.

Of the remaining British species, one (_P. Arenariæ_) is found on the
leaves of the three-veined sandwort (fig. 268); another attacks the red
corn-poppy, a third is found on the common nettle, one on the brooklime,
another on the wood-anemone (fig. 267), and another on the figwort.

Doubtless all the species in this genus are possessed of the third means
of reproduction, by zoospores, as discovered in the potato mould, not
only from the acrospores, but also from the oospores.


                               Plate XVI.

[Illustration:

  268.—SANDWORT MOULD.
  _Peronospora Arenariæ._
]

[Illustration:

  269.—DOCK MOULD.
  _Peronospora obliqua._
]


The fearful rapidity with which this method enables them to multiply
themselves may account for their widely spreading and devastating power.
No other genus of fungi can parallel this in the number of species
injurious to the field or the garden, or in which the injuries inflicted
are so great and irremediable.

                  *       *       *       *       *

N.B.—Since the foregoing chapter was in type, the Rev. M. J. Berkeley
informs us that both Mr. Broome and himself have examined the mould on
dock-leaves, to which we have given the name of _Peronospora obliqua_,
and have come to the conclusion that it is truly a member of that genus,
and not hitherto described; but they are also of opinion that it is the
same mould as one described by Dr. Montagne as _Ascomyces Rumicis_. We
concur with them in thinking it deficient in the important
characteristics of _Ascomyces_, and therefore retain its proposed name
of _P. obliqua_.


------------------------------------------------------------------------



                              CHAPTER XII.

                      _WHITE MILDEWS OR BLIGHTS._


NOTWITHSTANDING the inconvenience to ourselves of calling very different
fungi by the same common name of “mildew,” the popular mind does not
recognize the inconvenience, since it scarcely troubles itself to
inquire whether they are not all the same thing. In obedience to this
custom, we again write of “mildew,” or “blight,” as it is called in some
districts, but of a very different kind to that which is so detrimental
to growing crops of corn. In the present instance it is our intention to
illustrate a group of fungi which are exceedingly common, and which
differ greatly in appearance and structure from any to which we have had
occasion to allude. To obtain a general knowledge of these forms let our
reader proceed at once to a clump of rank grass; if it is his fortune to
dwell in the country, the walk of a few yards will suffice. Let him
examine this clump more carefully, perhaps, than he has been accustomed
to do, and we venture to predict that he will find some of the leaves
covered with what appears to be a dirty white mould, or mildew (Plate
XI. fig. 235). One of these leaves should be collected as carefully and
conveyed to the microscope as speedily as possible, taking care not to
touch, or brush it against any other object so as to disturb the
arrangement of the delicate little threads upon its surface. If a small
portion, say about an inch, is cut from this leaf with a sharp pair of
scissors, and laid upon a slide, or pinned down upon a strip of sheet
cork, so as to keep it flat, and then submitted to examination under the
microscope, with an inch power, a beautiful forest of crystalline
vegetation will be observed. If the examiner on this occasion should not
possess a binocular microscope we are sorry for him, because in that
case he will not see all that is to be seen under the greatest
advantages. If we ever truly enjoy looking through such an instrument,
it is on an occasion like this, when a low power is all that is needed,
and the object is required to be seen in relief. It is scarcely possible
to convey an adequate idea of the beauty of such a scene as the
microscope reveals upon this fragment of grass-leaf. Little bundles of
delicate threads, clear and crystalline, are seated upon a slender
branching mycelium. These threads, sometimes erect, sometimes drooping,
flexuous, or prostrate, are composed of numerous roundish or spherical
cells attached to each other in a moniliform or bead-like manner (fig.
236). These easily separate from each other. Let a portion of the
threads be removed from the leaf on the point of a lancet and laid upon
a glass slide, with a thin cover over them. Submit this object to a
quarter-inch power, as a drop of water is let fall at the edge of the
cover and insinuates itself, by capillary attraction, between the two
plates of glass. So soon as it touches the moniliform threads, the
disunion commences, and almost before they are enveloped in the fluid,
two spherules will scarce remain attached to each other. This delicate
little mould on the grass leaf at one time bore the name of _Oidium
monilioides_. It is now regarded only as a condition of another minute
fungus, to which attention will shortly be directed.

The vine disease, so fearfully destructive on the Continent, and not
altogether unknown in this country, is another of these incomplete
fungi. From an individual who at the time of its first discovery in the
south of England took considerable interest in the subject, it was
called _Oidium Tuckeri_, which name it continued to bear, both here and
abroad, until, with many others, probably nearly all of the same genus,
it was found to be only a barren state of what is called by mycologists
an _Erysiphe_. The real discoverer of this mildew was undoubtedly the
Rev. M. J. Berkeley, who has successfully devoted a long life to the
study of these minute organisms, through evil and through good report,
and when that study was beset with more difficulties, and received less
encouragement than at present. If, towards the autumn, we should again
collect some whitened, mouldy, or mildewed grass-leaves, similar in
appearance to those mentioned above, and carefully look at them with a
pocket lens, little black points, almost as small as a pin-point, or
more resembling the full stop with which, this sentence closes, will be
found scattered over the white threads. The aid of the microscope must
be again sought to make out the structure of the little black dots.
Closely nestling upon the mycelium, the little points will prove to be
spherical brownish, conceptacles, surrounded with transparent floccose
appendages. Many other species are far more beautiful than that of the
grass-leaf, as will be seen by reference to our plate. The variation
consists chiefly in the form of the appendages which spring from the
conceptacle and surround it in a radiating (as in figs. 219, 222, 225,
and 230), or in a more or less confused and entangled manner (as in
figs. 216, 240, 245, and 251). The surface of the conceptacle is
minutely reticulated, and its base is attached to the mycelium. When
first formed, these globose conceptacles are almost colourless; they
afterwards acquire a yellow colour, and are ultimately of a deep brown.
The appendages are seldom at all coloured. Within the conceptacle are
contained from one to several transparent obovoid sacs, or spore-cases,
called _sporangia_, enclosing a definite number of spores (figs. 218,
224, 228, &c.), which vary in different species. In the hazel mildew,
for instance, there are two spores in each _sporangium_; in the willow
mildew four; in the maple mildew eight; in the grass mildew, and some
others, numerous. The tips of the appendages are variable, and often
elegant (figs. 227, 231, 233, 234, and 247), sometimes simple and at
others symmetrically branched. All the species occur on the still living
and green parts of plants, especially the leaves, and are therefore
truly parasitic. A pocket lens will show whether any conceptacles are
present on any suspicious leaf which may be collected, but high powers
of the microscope are essential for their complete examination. It is
during autumn, when vegetation begins to languish, that we shall be most
successful in searching for specimens. They will then be found almost
everywhere, and the white mycelium forms an object too conspicuous for
them to be readily overlooked. Botanically, nearly all the species were
at one period included in one genus, under the name of _Erysiphe_, a
name derived from the Greek, and signifying “mildew;” at the present
time they are distributed through several genera, the chief distinctions
of which are based upon the form of the appendages. Though personally
disposed to question the generic value of such distinctions, it would be
imprudent to adopt any other names here than those to be found in recent
English works on fungi.

The first species in our enumeration is found on cultivated roses. What
a deplorable picture does a favourite rose-bush present when attacked by
this mildew! The leaves blistered, puckered, and contorted; their
petioles and the peduncles and calyces of the flowers swollen,
distorted, and grey with mould; and the whole plant looking so diseased
and leprous that it needs no mycologist to tell that the rose is
mildewed. The conceptacle in this species is minute, and contains but
one sporangium, which is one of the characters of the genus in which it
is now included, and a more justifiable distinction than the
ramifications of the appendages. The mycelium is rather profuse, and the
threads or appendages which spring from the conceptacle are simple and
floccose (fig. 216). The sporangium contains eight ovate spores. This
species (_Sphærotheca pannosa_, Lev.), in its oidioid or conidiiferous
form, was for some time known under the name of _Oidium leucoconium_.

An allied species constitutes the hop-mildew, a visitation with which
some of our Kentish friends are too familiar. This is not a prejudiced
species in the choice of its habitation, since it is found on many other
plants, where it flourishes with equal vigour. The meadow-sweet, burnet,
scabious, teasle, dandelion, and other composite plants, plantain, and
plants of the cucumber family, all suffer more or less from its roving
disposition. The mycelium of whitish threads is even more conspicuous
than in the last species, but the conceptacles are often not to be found
at all. These are also very minute and most common on the under surface
of the leaves. The appendages, or fulcra, are simple, floccose (fig.
217), and coloured. The sporangia are found singly in each conceptacle,
and each, sporangium contains eight spores.

An autumnal stroll amongst hazel-bushes, when the nuts are ripe, will
lead, if the nuts are not a greater attraction, to the discovery of
whitish, patches on the under surface of the leaves, caused by the
mycelium of the hazel mildew (_Phyllactinia guttata_, Lev.). These
patches are less distinct and conspicuous than in many other species,
but the little blackish dots of the conceptacles may be distinguished by
sharp eyes without the use of the lens. Though possessing a decided
preference for the hazel, this species is also found on the green leaves
of the hawthorn, ash, elm, birch, sallow, beech, oak, and hornbeam. The
conceptacles are larger than in the two preceding species, and somewhat
depressed above. The appendages are few (fig. 219), radiating, rigid,
and acicular, or like needles. Each conceptacle contains eight or more
sporangia, and each sporangium has from two to four spores (fig. 220).
This species being very common, its conceptacles large, and produced
copiously, and its appendages distinct, it will prove a good type with
which the student of these fungi may commence his examinations. This is
the only representative which we possess of the genus established by M.
Leveille for such of the _Erysiphei_ as have the conceptacle depressed,
and the appendages rigid and simple; by which features it is
distinguished from genuine species of _Erysiphe_.

Two species, also common, having many features agreeing with each other,
are found on the leaves of the maple and the willow. The willow blight
(_Uncinula adunca_, Lev.) is found irrespectively on various species of
poplar and willow (fig. 221). In size and external appearances, to the
unaided eye, it seems scarcely to differ from the preceding, but more
minute examination will show that in the appendages there is an
appreciable difference. Still rigid, but no longer aciculate, the tips
bent or curved like a little hook, or curled upon themselves (fig. 223),
radiating and numerous (fig. 222), and at length tending upwards. Many
sporangia are contained within each conceptacle, each of which is
furnished with four spores. The amateur must not be disappointed, if, on
examining mature conceptacles with a view to the discovery of the
sporangia, he finds only free spores. The investing membrane is very
delicate, and disappears generally as the spores are matured.

The “blight” or “mildew” which occurs on the common hedge-maple, as well
as on sycamore leaves, is exceedingly conspicuous when occurring on the
former plant. The whole bush often presents a hoary appearance as if
sprinkled with powdered chalk. In the spring, the under surface of the
leaves of the same plant are liable to become hoary from another cause.
The whiteness occurs in patches, has often a pinkish or violaceous tint,
and glistens like hoar-frost. This affection of the leaves was, at one
time, believed to be produced by a fungus which was called _Erineum
acerinum_, but now it is regarded as a diseased state of the tissues. In
the maple mildew, both surfaces of the leaves are alike affected, and
the little, dark, point-like conceptacles will be found studded over
both. It is not uncommon to meet with very white leaves, caused by the
mycelium, but which bear no fruit. The appendages in this species are
shorter than in the last (fig. 225), and the tips are bifid (fig. 226),
or divided into two short branches, each of which is bifid, and uncinate
or hook-shaped (fig. 227). The conceptacles contain not less than eight
sporangia, each of which encloses eight spores.

Amongst the parasites that prey upon the much abused berberry (which has
been charged in turn with producing the mildew in corn), is one which
causes the green leaves to assume a chalky appearance (fig. 229), though
less conspicuously than in the maple blight. This parasite is the
berberry mildew (_Microsphæria berberidis_, Lev.). In such localities as
the writer has met with the berberry suffering from mildew, he has
invariably found a larger proportion of leaves with the barren mycelium
than of those on which the conceptacles were developed. Perhaps in other
localities this may not be the case. The appendages, as will be seen on
reference to our plate, differ materially from any of those to which we
have referred; indeed, this genus (or sub-genus) has the most elaborate
and beautiful forms in these appendages of any of the Erysiphei. A
figure is given of the tip of a fulcrum from a continental species (_M.
Ehrenbergii_, Lev.), not yet found in this country (fig. 233). In the
berberry blight the appendages are straight at the base, but afterwards
become forked, each fork being again forked, and these yet again
branched in a similar manner (fig. 230); so that a complex dichotomous
tip is formed to each of the appendages (fig. 231). Each conceptacle
contains about six sporangia, and each sporangium contains from six to
eight spores (fig. 232).

The common gooseberry is also liable to a visitation from an allied
species, in many respects closely similar, but differing in having the
tips of the appendages more branched, and the extremities of the
ultimate branchlets are not entire and attenuated, as in the berberry
mildew; but divided into two toothlike processes. The conceptacles in
this species contain from four to eight sporangia, each of which has
four or five spores.

In England, the leaves of the guelder-rose, and in France (perhaps also
in this country) those of the alder, nourish a parasite belonging to
this division. This “blight” possesses so much in common with others to
which allusion has been made, that it will scarcely be necessary to
describe it in detail. A figure of the tip of one of the appendages of
the variety found on the alder is given in the Plate XI. fig. 234.

We have found another species which had not been before noticed in this
country (_M. Hedwigii_, Lev.), on the leaves of the mealy guelder-rose
in the vicinity of Darenth Wood, near Dartford, in Kent. The mealy
character of the leaves of this plant, and the minute size of the
conceptacles of the parasite, render it difficult to find; indeed, it
could not be noticed unless it were sought for, as we sought it, lens in
hand. It only occurs on the under surface of the leaves: the mycelium is
very web-like and fugacious, the conceptacles minute, globose, and
scattered (fig. 243). Four sporangia, each containing but four spores
(fig. 244), are enclosed in each conceptacle, which is surrounded by a
few appendages (about six) thrice dichotomous, and thickened at the tips
of the ultimate branches, which are incurved (fig. 247).

The species of true _Erysiphe_ are distinguished botanically from the
foregoing by the floccose character of the appendages, in which feature
they accord with the species found on the rose and the hop, but from
which they differ in the conceptacles containing numerous sporangia
instead of only one, as in those species.

One of the most common and conspicuous of these is found on the leaves
and leaf-like stipules of the garden pea. Every leaf in a crop will
sometimes suffer, and the gardener, to his great mortification, finds
that the mildew is more prolific than his peas. The leaves become sickly
and yellow as the mycelium of the fungus spreads over them, when they
present a peculiar appearance, as if growing beside a chalky road in dry
dusty weather, and had become covered with comminuted chalk. Soon the
conceptacles appear, profusely scattered over the white threads, like
grains of gunpowder (fig. 237), and after a brief struggle for existence
the pea and its parasite die together. In this species (_Erysiphe
Martii_, Lev.), the appendages are nearly transparent, short, and much
interwoven with the mycelium (fig. 238), the globose sporangia
containing from four to eight spores (fig. 239). It is not confined to
peas, although that habitat has been here given for it, because it is so
common upon them. Beans, melilot, St. John’s-wort, some umbelliferous
plants, and the meadow-sweet, have all been found affected.

The species found on grasses, especially the cocksfoot, has been already
alluded to. The conceptacles contain from twenty to twenty-four ovate
sporangia, each enclosing eight spores. The appendages and mycelium are
much interwoven.

Another of these “white mildews,” not only on account of its frequency
of occurrence on certain plants, but also from the numerous species of
phanerogamous plants on which it is found (fig. 240), may be truly
designated “common” (_Erysiphe communis_, Lk.); many kinds of crow-foot,
especially _Ranunculus acris_, are subject to its parasitism. It is
found also on other plants of the same natural order, on the
rest-harrow, trefoils, enchanter’s nightshade, bindweed, and knotgrass.
There are from four to eight sporangia in each conceptacle, containing
from four to eight spores (fig. 241). In this species, more especially,
M. Tulasne found curious sucker-like processes developed on the threads
of the mycelium (fig. 242): their office may probably be only that of
attachment.

Of the other species found in Britain an enumeration will suffice, since
they contain no feature of interest to the microscopist; and all the
members of this section are far less beautiful than those in other
genera (especially _Microsphæria_).

The leaves of the dogwood or cornel (figs. 245, 246) are the home of one
species (_E. tortilis_, Lk.), and the burdock of another (_E.
Montagnei_, Lev.). Both of these, in addition to the above, have
sporangia which contain more than two spores. There are also two species
in which only two spores are contained in each sporidium. One of these
(_E. Linkii_, Lev.) is found on both surfaces of the leaves of the
mugwort (figs. 248, 249); the other (_E. lamprocarpa_, Lev.) occurs on
salsafy, scorzonera, weasel-snout, and plantain (figs. 250, 251).

These complete the _Erysiphei_; but there are allied species of too much
interest not to be noticed in connection with them. Three very singular
fungi are found on damp straw and paper; two on the former and one on
the latter. Of the species occurring on straw, the most common one is
figured, natural size, in our plate (fig. 257); but from this no idea
can be formed of its structure, which in some points resembles an
_Erysiphe_. The conceptacles are thin and brittle, and are clothed
externally with long dark-coloured branched hairs (figs. 258, 259). The
conceptacle contains long narrow sporangia, each enclosing dark, almost
black, lemon-shaped sporidia. For low powers this is a very interesting
object. The minute structure affords no feature of popular interest.
This fungus (which bears the name of _Chætomium elatum_) is common on
old straw, thatch, reeds, matting, &c., resembling small brown tufts of
hair, visible to the naked eye.

Paper much exposed to damp will occasionally develop a similar
“bristle-mould,” surrounded by a yellowish spot (_Chætomium chartarum_,
Ehrb.); but it is not so common as the last. In habit and structure it
is very similar (figs. 252, 253).

In 1838, the Rev. M. J. Berkeley announced the discovery by him of a
singular production, for which he was unable to find a fitting location
in any genus then established, and for which he accordingly
characterized a new one, under the name of _Ascotricha_. This new
species of paper mildew was found by him on some printed paper in a box.
It somewhat resembles the other species above alluded to, at a casual
glance; but more minute examination will reveal its differences. The
author to whom we are indebted for this species thus describes its
development. At first it appears as a minute branched mould interspersed
with globose brownish conidia. As it advances in growth, globose black
peridia become visible amongst the threads, clothed with and supported
by alternately branched obscurely-jointed filaments, the branches of
which generally form an acute angle with the stem (fig. 254). The
ramification of these is very peculiar, the stem and main shaft of each
sub-division being almost constantly shortened and surmounted by the
branches given off near its apex; this, again, is often abbreviated and
another branchlet given off, which again surpasses it; and occasionally
the same circumstance takes place a third time. The apices are clavate
and colourless; the rest of the filaments, when viewed by transmitted
light, brown, even, and pellucid: a few globose conidia are usually
attached to them (fig. 255). The conceptacle is thin, black to the naked
eye, of an olive-brown under the microscope, filled with a mass of
linear extremely transparent asci (fig. 256), each containing a single
row of broadly elliptic chocolate sporidia. These have a paler border;
sometimes the colour entirely vanishes, either from age or abortion, and
there is only a minute globose nucleus or more probably a vesicle of
air, in the centre; occasionally they become so transparent that the
globular bodies alone are visible. After the conceptacles burst, several
are frequently collected together into an irregular linear body, which
consists principally of the conglomerated sporidia.

One other very common and troublesome little fungus (_Eurotium
herbariorum_) will for the present close our examples. This is found
creeping over dried plants preserved in herbaria, on decaying fruit,
preserves, and various other substances, sometimes animal as well as
vegetable, but chiefly the latter. To the naked eye it appears as a
myriad of little yellow spherical bodies, of the size of very small
pins’ heads, resting upon fine cobweb-like threads (fig. 260). When
magnified, the surface of the conceptacles is seen to be reticulated
(fig. 261). In the interior the sporidia are borne, contained also, as
in the former instance, in asci. It has been considered _probable_, but
as yet not fully proved, that this mildew is a compound fruited
(ascigerous) condition of an equally common mould (_Aspergillus_).

Dr. Shortt, of Chingleput, in a recent report on the growth and
production of Indian Cotton, remarks that the plants are subject to the
attacks of a kind of mildew. He writes:—“They appear in the form of
rounded fibres or thallus, shooting up in the air, having the lamina of
the leaf as a base, and feeling villous to the touch. The small fibrillæ
that form the nap appear shooting up as sharp projections when seen by
the naked eye; under the microscope they are found to consist of pointed
tubes, interspersed here and there with minute granular cells. It first
attacks either the upper surface of the petioles, or the margins of the
leaf, gradually extending over the lamina, and matting together the
whole leaf into a greyish-white, felty mass. At first it attacks the
young shoots and tender leaves, preventing them from expanding. The
extension of the parasite deprives the plant of its juices, and
eventually either destroys or renders it sterile. The spores seem to be
derived from the atmosphere, and finding the plant in a state fit to
receive them, from either the results of excessive cultivation, or from
the effects of heat and want of moisture rendering it unhealthy, and
thus favouring the reception of the spores of the fungi. Another variety
speckles the leaves with whitish dots. These remain separate, but the
lamina is covered with them, and in time the leaf changes colour,
becomes yellowish, and eventually dies away. This is evidently the
disease called _Bunt_, or some variety of it, as it is seated beneath
the epidermis, and eventually the spores escape. Under the microscope
they seem to consist of small dark cells or spots attached to a
thread-like mycelium.”

The writer seems certainly to have made a mistake in its affinities, and
on the faith of the above quotation we should be more disposed to regard
it as an _Erysiphe_. It is to be hoped that specimens of the affected
leaves will be forwarded to this country for examination.


------------------------------------------------------------------------



                             CHAPTER XIII.

                             _SUGGESTIONS._


IF, in offering a few practical suggestions, we either repeat ourselves,
or communicate common-place hints, those who may know already all we
shall essay to tell them will please to pardon and pass on.

All the information essential under this head relates to collecting,
examining, and preserving microscopic fungi.

Collecting does not differ, except in the objects themselves, from any
other botanical collecting. Those who attempt it must be prepared to
sacrifice their kid gloves and patent-leather boots, to put on
waterproofs and perseverance, and come home sometimes disappointed. The
requisites for good work are but few, and easily supplied. A strong
knife, a pocket lens, and a box or leather bag, will be all that is
really essential. But where shall we go—and when? Hedge-banks, the sides
of ditches, borders of woods, anywhere, if the plants are to be found on
which the fungi are parasitic. We flatter ourselves on being rather
successful in collecting, and our favourite localities have always been
the dampest places in woods, railway-banks, and waste places. It is a
great mistake to endeavour to go over a large tract of ground. We have
spent a whole day in a little chalkpit, which had fallen into disuse,
and grown wild. Fifty yards into a wood is as much, as we attempt, when
alone; and a spot six yards square has afforded us occupation for hours.
It is better to examine a small space thoroughly than to scamper on,
mile after mile, and find nothing.

When? is as much to be noted as where! All the year round we shall be
sure of finding something of interest. As soon as the last patch of
winter’s snow has melted from the ground, and green leaves begin to
unfold themselves, the search may begin. Cluster-cups (_Æcidium_) will
be the earliest forms encountered. On the leaves of _Lapsana communis_,
and the pilewort, these will be found before the majority of plants have
burst their buds. Henceforth, other forms will gradually appear, until
May or June. One or two species of _Puccinia_ will be seen in April or
May, but from that period until autumn, species of _Trichobasis_ will be
common. In June and July the smuts belonging to the genus _Ustilago_ are
most plentiful, and from August to October _Puccinia_ and its allied
genera will have the ascendant; so that from March to October there is
continually succeeding each other some species of parasitic fungus
belonging to the Uredines. From October to March need be no more a
season of repose from the search of these minute plants than from March
to October. So long as the ground is not covered with snow there will
always be something to find on dead leaves, rotten sticks, &c., when
there is not a green leaf to be seen. But these belong to a section to
which we have studiously avoided all reference in the foregoing pages.

General instructions will not always apply; but in most instances, the
lowest and earliest leaves, in which vitality appears to decline, will
be most likely to suffer from the attacks of fungi. This rule must not
be too stringently applied; the species of _Æcidium_, for instance, will
generally be found on vigorous green leaves.

Having found a plant infected with some rust or brand, and by means of a
pocket lens assured yourself that it is such, although the power is
insufficient to tell what it is, collect as many leaves as you are
likely to require; place them flat one upon the other, to prevent their
curling up at the edges, should the weather be hot, and yourself far
from home, and lay them in your box; or if you should take in preference
an old book with stiff covers, place them separately between the leaves
of your book, and they will be in still better condition, if you desire
to preserve them. Arrived at home with the results of your trip, proceed
at once to lay them between folds of blotting-paper, submit them to a
gentle pressure, and change the papers daily until your leaves are dry,
not forgetting to keep a scrap of paper with each collection, stating
date and locality, to which, after microscopical examination, the name
may be added. When thoroughly dry, your leaves may be preserved for
reference in old envelopes, with the particulars endorsed on the
outside. Fungi on leaves will generally be examined to the greatest
advantage in the fresh state, but if too much pressure is not employed
in the drying, it will not be difficult even in that condition to make
out their characteristic features. Care must be taken, by changing their
position, that moulds of other kinds do not establish themselves upon
the specimens in drying, or that when dried they do not fall a prey to
_Eurotium herbariorum_.

If it is intended to add these leaves to your herbarium, or to form a
special herbarium for them, they should be mounted on white paper, first
by affixing one or two leaves by means of thin glue to a paper about
four inches square, on which the name, date, and locality may be
written, and attaching several of these _species_-papers to a larger or
_genus_-paper, or by devoting each larger paper to a species, adding in
future other varieties, and enclosing all the _species_-papers of the
same genus within a folded sheet, on which the name of the genus is
written.

We have adopted, for our own herbarium, the “foolscap” size. A sheet of
paper receives within its fold the specimens of a single species; these
are affixed to the right-hand page, when the sheet is open, and a small
envelope is attached by its face to the same page at the bottom, in
which loose specimens are kept for minute and special examination, or as
duplicates. When the sheet is folded, the specific name is written at
the right-hand lower corner, or, what is better, a strip containing that
name and its number is cut from a copy of the “Index Fungorum,” kept for
the purpose, and gummed in its place. The remainder of this page, which
is of white cartridge paper, is occupied with memoranda referring to the
species enclosed, sketches of the spores, synonyms, references to
descriptions, &c. All the species-papers of each genus are placed
together within a sheet of brown paper, half an inch larger in each
direction, with the name of the genus written at the left-hand corner. A
piece of millboard, the size of the covers when folded, separates each
order.

When a leaf, or other portion of a plant, is to be examined under the
microscope, with the view of determining the genus and species of its
parasite, it may be fastened with small pins to a piece of sheet cork,
two or three inches square, and about one-eighth of an inch in
thickness, such as used for lining entomological cabinets, and so placed
under a lens that it may easily be brought into focus, and both hands
left at liberty; or a dissecting microscope may be used for the purpose.
From one of the pustules the spores may be removed on the sharp point of
a penknife, and placed in a drop of water on a glass slide. A thin glass
cover is placed over the drop of water, and the slide is submitted to
examination. For further satisfaction it will often be found necessary
to make carefully a thin section of a pustule, and place this under the
microscope, a more troublesome but also much more satisfactory method.
Reference to the Appendix will soon determine the name and position of
the fungus, provided it belongs to the section to which this volume is
devoted.

If it is thought desirable to mount the spores as permanent objects,
there is no obstacle to such a proceeding. The spores of the different
species of _Aregma_, of _Triphragmium_, and many of the _Pucciniæ_, will
be worth the trouble. We have tried several media, and only adopted
Glycerine or Balsam; either of these, especially the former, if the
greater difficulty of securely closing can be overcome, will answer the
purpose.

It should be remarked that in the examination of moulds, such as those
of the genus _Peronospora_, included in this work, if any fluid be
added, the acrospores are immediately disconnected from the threads, and
float in the medium; so that if their mode of attachment or arrangement
would be studied, that must be achieved without the addition of any
fluid whatever.

The best methods of observing germination, the production of zoospores,
&c., have been detailed already.

Thus do we arrive at the close of the task which we had set ourselves to
perform. This fragment of a history of microscopic fungi goes forth to
plead for students, and prepare the path for somewhat more complete. Is
it not a shame that more than two thousand species of plants (never mind
how minute, how insignificant) should be known to exist, and constitute
a flora, in a nation amongst the foremost in civilization, and yet be
without a complete record? It is nevertheless true that hundreds of
minute organisms, exquisite in form, marvellous in structure, mysterious
in development, injurious to some, linked with the existence of all, are
known to flourish in Britain without a history or description, in the
language of, or produced in, the country they inhabit. It is also true
that the descriptions, by which they should be known, of hundreds of the
rest lie buried in a floating literature whence the youthful and ardent
student needs, not only youth and ardour, but leisure and perseverance
unlimited to unearth them. This, however, by the way; we may be too
great dotards on our native land, and foolish in our desire to see her
in advance, and not in the rear in scientific attainments, pursuits, and
productions of other and, perhaps, less favoured nations.

Already we fear that some of our readers will have thought our story of
rust, brand, and mildew interminable, and looked anxiously for the
close. On the other hand, we would flatter ourselves into the belief
that some have made a new acquaintance with these minute and mysterious
forms, and would fain know more. The groups of fungi which we have
endeavoured to illustrate have, with but few exceptions, one feature in
common, _i.e._, that they are parasitic on living plants. These
constitute but a small portion of the microscopical species found in
this country. To the elegant forms of mould which inhabit decaying
vegetable substances no allusion has been made. These constitute a fairy
flora of forests and gardens with features as varied, and fruits as
multiform, as those of the trees and flowers of the earth. The numerous,
and often marvellous, phases of low life developed upon dead leaves and
rotten sticks, would in description occupy a far greater space than we
have devoted to our subject. Yet, for all these, we have not spared so
much as a passing word. The treasures still left unopened are far richer
than even those we have revealed. The gates of another world have been
thrown open, but we have scarcely passed the threshold. A minutely and
elaborately illuminated page of the book of Nature has been turned, and
we have only perused a single line. We might traverse the primeval
forests of the new world, and explore the unknown regions of the old,
and not encounter so much to excite our admiration, or cause our wonder,
as lies about our feet at home; marvels which we tread beneath our feet,
or kick from our path, because they appear to be only rotten sticks,
withered grass, and decaying leaves. All this may appear as the dream of
an enthusiast, or the ravings of one on whom the moon has shone too
often. When Columbus spoke of a new world beyond the seas, which he
longed to seek and explore, some believed him duped, and others called
him mad. We write of no chimerical El Dorado, we speak of no
undiscovered world, and yet we seem to allude to wonders still unknown,
because so few have had the courage to venture upon the journey for
themselves.

In sober earnestness, however, let us commend this pursuit to all who
possess a microscope and leisure to use it. It may be for a time the
“pursuit of knowledge under difficulties,” on account of the condition
of our literature on this special subject; but many workers will produce
more readers, and good books will come when there are more to purchase
and appreciate. It is not improbable that in more cases than have come
under our own observation, microscopists wearied of diatoms and allied
forms, or deeming themselves in possession of all that is novel or
interesting in this direction, are seeking for a new field of labour,
and a new subject to kindle up a new enthusiasm. To these we have
advised, and to any more such we continue to advise, that fungi should
have a fair trial. If variety is desired, here they will have at least
2,000 species for a knowledge of which the microscope is essential. If
they thirst for discovery, let them be assured that here also the
earnest worker is sure to meet with such a reward. Or if they would
acquaint themselves with the manifestations of Divine power as developed
in the most minute of created things, let them follow such observers as
Tulasne and De Bary, and seek the “why and the wherefore” of the
phenomena of mycetal life.

If there should still be any hesitation whether there is in this pursuit
sufficient of the element of variety, for those who do not desire to
pursue the subject into its deepest scientific recesses, to render it
available for them, let them go to a good public library, such as that
of the British Museum, and inquire for the large illustrated work by
Corda, entitled “Icones Fungorum,” or the more recent volumes by Tulasne
(Selecta Fungorum Carpologia), and examine the figures of microscopic
fungi in either of those works, and decide for themselves.


------------------------------------------------------------------------



                              APPENDIX A.

                               ----------

    CLASSIFICATION & DESCRIPTIONS OF FUNGI CONTAINED IN THIS VOLUME.

                                -------


                              =ÆCIDIACEI=.

          Peridium elongated—

              separating in threads           _Rœstelia_.

              rupturing irregularly           _Peridermium_.

          Peridium abbreviated, or            _Æcidium_.
          semi-immersed

          Peridium immersed                   _Endophyllum_.


                            RŒSTELIA, _Reb._

    _Peridium_ elongated, at length opening by lateral fissures, or a
        terminal lacerated mouth. _Spermogonia_ on the opposite surface,
        on the same or on different leaves.

=Rœstelia cancellata=, Reb. PEAR-LEAF RŒSTELIA; spots yellow, then red,
prominent; peridia split to the base into laciniæ, which remain united
at the apex.—On Pear leaves. Not very common. Autumn. (Plate II. figs.
20, 21.)

=Rœstelia cornuta=, Tul. HORN-LIKE RŒSTELIA; spots rusty-brown; peridia
cylindrical, slightly curved, yellowish-brown; spores greyish, at length
brown.—On the under surface of the leaves of Mountain-Ash. Not common.
August. (Plate II. figs. 18, 19.)

=Rœstelia lacerata=, Tul. LACERATED RŒSTELIA; peridia clustered in
tufts, brown, elongated, splitting to the base in segments; spores light
brown.—On the under surface of the leaves, and on the petioles and fruit
of the Hawthorn. Not uncommon. May to July. (Plate II. figs. 22, 26.)


                          PERIDERMIUM, _Chev._

    _Peridium_ elongated, at length bursting irregularly. _Spermogonia_
        scattered, conspicuous.

=Peridermium Pini=, Chev.; peridia oblong, scattered, large; spores
orange, abundant; spermogonia vernal or autumnal, or both; spermatia
large, white.—On leaves and young branches of Scotch Fir. Common in
Scotland, occasional in England. Summer. (Plate II. figs. 27, 28.)

=Peridermium elatinum=, Lk.; simple, immersed; peridia elliptic, pallid;
sporidia orange.—On Silver Fir, altering both foliage and ramification.
Not common.


                            ÆCIDIUM, _Pers._

    _Peridium_ seldom elongated, opening by a terminal mouth, surrounded
        by a fringe of recurved teeth, or when short bursting
        irregularly. _Spores_ disposed in chains. _Spermogonia_ on the
        same or the opposite surface, clustered or scattered, central or
        intermixed.

    SECT. I.—_Peridia scattered_ (_not collected in tufts or clusters_).

=Æcidium leucospermum=, DC. WHITE-SPORED CLUSTER-CUPS; spots yellowish;
peridia scattered, often covering the whole under surface; spores white,
ovate.—On both sides of the leaves of the wood-anemone. Common. June.
(Plate I. figs. 4-6.)

=Æcidium quadrifidum=, DC. FOUR-LOBED CLUSTER-CUPS; spots brownish;
peridia scattered, occupying almost the entire under surface; spores
brown, subglobose.—On the under side of leaves of Anemone in gardens.
(Lobes at the mouth of the peridium not constantly four.) April to May.

=Æcidium albescens=, Grev. MOSCHATEL CLUSTER-CUPS; leaf blistered,
whitish, scattered; peridia white, split into a few large teeth; spores
yellowish-white.—On leaves and petioles of _Adoxa moschatellina_. Not
uncommon. April.

=Æcidium Epilobii=, DC. WILLOW-HERB CLUSTER-CUPS; spots obliterated;
peridia scattered, at length oval, wider above; spores orange, at length
brown.—On the under side of leaves of _Epilobium montanum_, _E.
hirsutum_, and _E. palustre_, rarely on the upper. Common. June to
August.

=Æcidium Thesii=, Desv. BASTARD-TOADFLAX CLUSTER-CUPS; spots
obliterated; peridia scattered or biseriate; short, cylindrical, margin
irregularly toothed, erect; spores yellowish, then dingy.—On _Thesium
humifusum_. Downs near Winchester. July, 1864. Chipstead, Surrey, Oct.
14, 1864. (Plate III. figs. 50, 51.)

=Æcidium Soldanellæ=, Hornsch. SOLDANELLA CLUSTER-CUPS; spots
obliterated; peridia solitary, scattered over the inferior surface;
spores orange.—On the under surface of the leaves of _Soldanella
alpina_.

=Æcidium Tragopogonis=, Pers. GOATSBEARD CLUSTER-CUPS; spots
obliterated; peridia scattered, torn, wider above; spores orange, at
length black.—On stems, leaves, and involucres of common Goatsbeard.
Very common. May to June. (Plate I. figs. 1-3.)

=Æcidium Euphorbiæ=, Pers. SPURGE CLUSTER-CUPS; spots obliterated, leaf
thickened; peridia scattered or crowded, distinct; spores orange.—On the
under surface of the leaves of Spurge. Common. May to June.


               SECT. II. _Peridia in tufts or clusters._

                             α. _Elongatæ._

=Æcidium Berberidis=, Pers. BERBERRY CLUSTER-CUPS; spots roundish,
bright red; subiculum thickened; peridia in subrotund or oval patches,
often elongated; spores orange.—On leaves, peduncles, and fruit of the
common Berberry. Common. May to July. (Plate I. figs. 7-9.)

=Æcidium Thalictri=, Grev. MEADOW-RUE CLUSTER-CUPS; collected in
roundish clusters; peridia oblong; spores bright orange.—On _Thalictrum
alpinum_. Not uncommon in Scotland.

=Æcidium crassum=, Pers. BUCKTHORN CLUSTER-CUPS; spots yellow-brown,
subiculum thickened; peridia crowded into a roundish heap, at first
globose, yellow, at length open; spores orange.—On _Rhamnus catharticus_
and _R. frangula_. Common.

=Æcidium Periclymeni=, DC. HONEYSUCKLE CLUSTER-CUPS; spots variegated,
yellow and brown, subiculum thickened; peridia sometimes elongated, in
roundish or effused heaps; spores orange.—On the under surface of
Honeysuckle leaves. Not common. June to August.


                           β. _Poculiformæ._

=Æcidium Calthæ.= Grev. MARSH-MARIGOLD CLUSTER-CUPS; aggregate; peridia
somewhat campanulate, with numerous minute marginal teeth; spores bright
orange, subglobose or oval.—On leaves and petioles of _Caltha
palustris_. Margin of peridia pale and brittle. Rare. Spring.

=Æcidium Ranunculacearum=, DC. CROWFOOT CLUSTER-CUPS; spots obliterated,
subiculum thickened; peridia in irregular heaps, densely crowded
together; spores orange.—On leaves of various _Ranunculaceæ_; very
common on _R. Ficaria_, not uncommon on _R. repens_, more rarely on _R.
acris_ and _R. bulbosus_. Spring. (Plate II. figs. 12-14.)

=Æcidium Galii=, Pers. BEDSTRAW CLUSTER-CUPS; spots linear or oblong,
obscurely brown; peridia scattered, rarely aggregate, dentate, whitish;
spores white.—On the leaves of _Galium verum_ and _G. mollugo_. (Plate
II. figs. 15-17.)

I am doubtful whether the _Æcidium_ on _Galium mollugo_ is really this
species.—(_M. C. C._)

=Æcidium Bunii=, DC. PIG-NUT CLUSTER-CUPS; spots obliterated, subiculum
thickened; peridia in irregular subrotund or oval heaps; spores
orange.—On _Bunium bulbocastanum_ and _Pimpinella saxifraga_. Spring.

=Æcidium Valerianacearum=, Dub. VALERIAN CLUSTER-CUPS; hypogenous,
rarely cauline, spots on a thickened subcircular or oblong base; peridia
scattered, more or less crowded, cup-shaped, tawny, margin erect,
denticulate; spores dirty-yellow.—On _Valeriana officinalis_ and _V.
dioica_. North Britain.

=Æcidium Asperifolii=, Pers. BORAGE CLUSTER-CUPS; clusters subrotund, on
a slightly thickened subiculum; peridia scattered; spores
yellowish-white.—On leaves of various _Boragineæ_. Summer. The parts of
the leaves on which it occurs are rendered concave on one side and
convex on the other.

=Æcidium Grossulariæ=, DC. GOOSEBERRY CLUSTER-CUPS; spots yellow, bright
red on the opposite side, with a yellow border; peridia crowded in
roundish heaps, at length brown, and surrounded with a brown area;
spores orange.—On leaves and fruit of Gooseberry and Currant. Common.
May to June.

=Æcidium Urticæ=, DC. NETTLE CLUSTER-CUPS; spots obliterated, subiculum
thickened; peridia disposed in elongated or subrotund heaps, at first
subglobose, then gaping; spores orange.—On leaves and stems of Nettles,
distorting them very much. Common. June. (Plate I. figs. 10, 11.)

=Æcidium Behenis=, DC. BLADDER-CAMPION CLUSTER-CUPS; spots yellow, brown
on opposite side; peridia somewhat circinating, in subrotund heaps;
spores brown.—On _Silene inflata_. Not common. Some of the peridia are
short and open, others larger and closed.

=Æcidium Orobi=, DC. BITTER-VETCH CLUSTER-CUPS; spots yellow, effused;
peridia scattered and disposed in small heaps; spores at length
white.—On stems and leaves of _Orobus tuberosus_. Scotland.


                            γ. _Subimmersæ._

=Æcidium Compositarum=, Mart. COMPOSITE CLUSTER-CUPS; spots purplish,
subrotund, confluent above; peridia crowded, in orbicular patches, or
circinating, on the under surface; spores orange, oval.

Var. _a._ _Taraxaci_, Grev.; clusters small, scattered.—On leaves of the
Dandelion. June to July.

Var. _b._ _Prenanthis_, Pers.; spots circular or irregular, purplish;
subiculum incrassated.—On leaves of Hawkweed (_Hieracium paludosum_).
Summer.

Var. _c._ _Tussilaginis_, Pers.; clusters round, on a thickened base;
peridia circinating.—On the under surface of leaves of Coltsfoot and
Butter-bur. Common. Autumn.

Var. _d._ _Jacobæa_, Grev.; pustular, soon becoming agglomerated,
numerous, depressed; peridia splitting into short, brittle,
yellowish-white teeth.—On leaves of _Senecio Jacobæa_ and _Sonchus
arvensis_. June to August.

Var. _e._ _Lapsani_, Purt.; spots purplish, irregular, confluent, on
both sides of the leaves; peridia amphigenous, in irregular patches or
scattered, not prominent, teeth numerous, minute, reflexed; spores
yellow, oval.—On both surfaces of the leaves of _Lapsana communis_.
April. Not uncommon.

=Æcidium Saniculæ=, Carm. SANICLE CLUSTER-CUPS; spots purplish, slightly
incrassated, small, scattered, roundish; peridia in small circulate
clusters, hypogenous, and on the petioles, at first hemispherical, at
length open, margin with from 4 to 6 spreading lobes; spores yellowish,
elliptical.—On the under surface of the leaves and on the petioles of
_Sanicula Europæa_. Not uncommon. May and June.

=Æcidium Violæ=, Schum. _Violet Cluster-Cups_; spots yellowish; peridia
in irregular heaps, seriate and scattered; spores orange, at length
brown.—On leaves, petioles, and sepals of Violets. Common. May and June.

=Æcidium Poterii=, Cooke. BURNET CLUSTER-CUPS; spots obliterated,
clusters subrotund or elongated; peridia hypogenous and on the petioles,
circinating or scattered, immersed, margin irregularly fringed with
numerous minute teeth, soon falling away; spores yellowish, oval.—On the
under surface of the leaflets and on the petioles of _Poterium
Sanguisorba_. Rare. May and June. Dartford Brent, Kent.

=Æcidium Geranii=, DC. CRANESBILL CLUSTER-CUPS; spots yellow and purple;
peridia in circinating clusters; spores yellow, at length brown.—On the
under surface of leaves of _Geranium pratense_ and _G. dissectum_. Not
common.

=Æcidium Menthæ=, DC. MINT CLUSTER-CUPS; spots obliterated; subiculum
thickened; peridia scattered, emersed, or aggregate immersed; spores
orange, elliptic.—On various Mints. Common.

=Æcidium Scrophulariæ=, DC. FIGWORT CLUSTER-CUPS; spots yellowish;
peridia in roundish circinate clusters (rarely scattered) on the under
surface; spores whitish, becoming tawny.—On the leaves of _Scrophularia
aquatica_. Thame and Sydenham, Oxon.

=Æcidium Pedicularis=, Lobosch. RED-RATTLE CLUSTER-CUPS; spots
obliterated, subiculum thickened; peridia thickly and irregularly
clustered, subimmersed; spores dirty, pallid orange.—On petioles,
leaves, and stems of _Pedicularis palustris_. Not common.

=Æcidium Primulæ=, DC. PRIMROSE CLUSTER-CUPS; spots obliterated; peridia
solitary, scattered, and crowded, hypogenous; spores whitish-yellow.—On
the under surface of leaves of Primroses. Not common. May.

=Æcidium rubellum=, Pers. DOCK CLUSTER-CUPS; spots purple; peridia
circinating, centre free; spores yellowish-white.—On leaves of Dock and
Sorrel. Not uncommon in moist localities. May and June.

=Æcidium Ari=, Berk. WAKE-ROBIN CLUSTER-CUPS; spots round, confluent;
peridia circinating, not crowded, central ones abortive.—On leaves of
_Arum maculatum_. Not common. June and July.

=Æcidium Dracontii=, Schwein. ARUM CLUSTER-CUPS; spots pallid,
extensively scattered over the leaves, sometimes nearly covering them;
peridia large, scattered, abundant, disposed without order on the spots;
spores orange.—On _Arum triphyllum_, in gardens. Melbury, 1863 (_Rev. M.
J. B._) A North American species.

=Æcidium Allii=, Grev. GARLIC CLUSTER-CUPS; spots pale; peridia
circinating, not contiguous; spores yellowish.—On leaves of broad-leaved
Garlic (_Allium ursinum_). June and July.


                          ENDOPHYLLUM, _Lév._

_Peridium_ enclosed within the substance of the leaf, bursting
irregularly.

=Endophyllum Sempervivi=, Lév.; peridia immersed, elliptic or roundish;
spores ochraceous, becoming brownish.—On leaves of Houseleek.


                               PUCCINIÆI.

                        _a._ _Spores stipitate._


          Spores multiseptate—
              moniliform                      _Xenodochus_.
              cylindrical                     _Aregma_.
              biseptate                       _Triphragmium_.
              uniseptate                      _Puccinia_.

                  _b._ _Spores immersed in gelatine._

          Stroma tremelloid and expanded      _Gymnosporangium_.
              clavate or club-shaped          _Podisoma_.

                           XENODOCHUS, Schl.

    Spores multiseptate, moniliform, breaking up into many distinct
        articulations.—_Berk. Outl._, pp. 328.

=Xenodochus carbonarius=, Schl. BURNET CHAIN-BRAND; scattered, in small
tufts, hypogenous; spores curved or straight, composed of from 5 to 15
articulations; obtuse at one extremity, slightly attenuate at the
other.—On Burnet. Very rare. (Plate III. fig. 29.)


                              AREGMA, Fr.

    Spores cylindrical, multiseptate, scarcely moniliform, borne on a
        long peduncle.—_Berk. Outl._, p. 329.

=Aregma mucronatum=, Fr. ROSE BRAND; hypogenous, scattered over the
leaves in minute tufts; spores 5- to 7-septate, terminal joint
mucronate; peduncles incrassated below, fusiform.—On leaves of various
Roses. Autumn. Frequent. (Plate III. fig. 38.)

=Aregma acuminatum=, Fr. BURNET BRAND; hypogenous, scattered in minute
tufts; spores multiseptate, terminal joint acuminate; peduncles
equal.—On Burnet leaves. July. Common. (Plate III. fig. 32.)

=Aregma bulbosum=, Fr. BRAMBLE BRAND; hypogenous, with a dull red stain
on the upper surface; spores in large tufts, 4-septate, terminal joint
apiculate; peduncles incrassated, and bulbous at the base.—On Bramble
leaves. Autumn. Very common. (Plate III. fig. 41.)

=Aregma gracile=, Berk. RASPBERRY BRAND; hypogenous, scattered, in small
tufts; spores 7- to 9-septate, the terminal joint apiculate; peduncles
slender.—On Raspberry leaves. Autumn. (Plate III. fig. 43.)

=Aregma obtusatum=, Fr. STRAWBERRY BRAND; hypogenous, scattered, in
minute tufts; spores multiseptate, terminal joint obtuse; peduncles
equal.—On leaves of barren Strawberry. Autumn. Common. (Plate III. fig.
35.)


                           TRIPHRAGMIUM, Lk.

    Spores trilocular, septa mostly vertical and horizontal.—_Berk.
        Outl._, p. 332.

=Triphragmium Ulmariæ=, Lk. MEADOW-SWEET BRAND; spots obliterated; sori
at first subrotund, covered with the epidermis; at length, when the
cuticle has vanished, effuse; spores brown, subturbinate, divided by a
vertical dissepiment, shortly pedicellate.—On leaves of Meadow-sweet,
_Spiræa ulmaria_. Autumn. (Plate III. fig. 48.)


                            PUCCINIA, Pers.

    Spores uniseptate, supported on a distinct peduncle.—_Berk. Outl._,
        p. 329.

=Puccinia graminis=, Pers. CORN MILDEW; spots pale, diffuse; sori
linear, confluent, amphigenous; spores at length black, clavate, very
slightly constricted.—On the leaves and culms of corn and grass. Autumn.
Very common, and injurious to corn. (Plate IV. figs. 57-59.)

Var. _β. Arundinis_, Grev. Sori broad; spores more constricted and with
longer peduncles.—On the leaves and sheaths of reeds. Very common.

=Puccinia striola=, Lk. SEDGE MILDEW; spots pallid; sori linear,
crowded, distinct, subconvex; spores at length black, oblong and
slightly constricted, or obovate, and not constricted.—On Sedges,
Rushes, &c. Autumn. Common.

=Puccinia coronata=, Cd. CORONATED MILDEW; spots pallid; sori linear,
short, crowded, not confluent, surrounded by the ruptured epidermis;
spores shortly pedicellate, pallid; the apex surrounded by obtuse
radiating teeth.—On various Grasses. Autumn. Not uncommon. (Plate IV.
figs. 60-62.)

=Puccinia truncata=, B. and Br. IRIS BRAND; spots obliterated; sori
oblong, brown, surrounded by the scarious epidermis; spores
obovate-oblong, even, attenuated below, upper cell abruptly truncate.—On
_Iris fœtidissima_. Autumn.

=Puccinia Asparagi=, DC. ASPARAGUS BRAND; spots none; sori
reddish-brown, generally on the stems, scattered and crowded, surrounded
by the ruptured epidermis; spores oblong, obtuse, constricted; peduncle
white, long, thread-like.—On dead stems of _Asparagus_. Autumn.

=Puccinia Polygonorum=, Lk. POLYGONUM BRAND; spots yellowish; sori
minute, crowded into orbicular patches; spores brown-black,
obovate-oblong, frequently constricted, with the upper joint globose.—On
the under surface of the leaves of various species of _Polygonum_.
Autumn. Common.

=Puccinia vaginalium=, Lk. KNOTGRASS BRAND; spots none; sori hypogenous,
subrotund or oblong, at first surrounded by the ruptured epidermis;
spores brown, obtusely ovate; pedicels long, filiform.—On leaves and
stems of Knotgrass, _Polygonum aviculare_. Autumn.

=Puccinia Thesii=, Chaill. BASTARD-TOADFLAX BRAND; cauline and
amphigenous; sori blackish-brown, small, roundish, or oblong, convex,
scattered or aggregate, surrounded by the ruptured epidermis; spores
ovate, obtuse, scarcely constricted; pedicels elongated.—On _Thesium
humifusum_, in company with _Æcidium Thesii_. Chipstead, Surrey, Oct.
14, 1864. (_A. Grugeon._)

=Puccinia Primulæ=, Grev. PRIMROSE BRAND; hypogenous, deep brown,
solitary, scattered, or concentric and subconfluent spores
obovate-oblong, slightly constricted.—On Primrose leaves. Not common.

=Puccinia Veronicarum=, DC. VERONICA BRAND; spots yellowish; sori
subglobose, aggregate, or circinating, central one large; spores brown,
obovate-oblong, more or less constricted.—On the under surface of the
leaves of several species of _Veronica_. Not common.

=Puccinia Glechomatis=, DC. GROUND-IVY BRAND; spots brownish; sori
subrotund, scattered, hypogenous; spots brown, rather short,
subelliptic, scarcely at all constricted.—On leaves of Ground-Ivy,
_Glechoma hederacea_. September and October. Not uncommon. (Plate IV.
figs. 73, 74.)

=Puccinia Menthæ=, Pers. MINT BRAND; spots obliterated; sori varying in
size, hypogenous, subrotund, scattered; spores at length black,
subglobose, or angular; peduncles short.—On leaves of Mint, Wild Thyme,
Marjoram, &c. Autumn. Common. (Plate IV. figs. 69, 70.)

=Puccinia Scorodoniæ=, Lk. WOOD-SAGE BRAND; spots obliterated; sori
small, confluent in subrotund patches, hypogenous; spores cinnamon;
peduncles very long.—On leaves of Wood-sage. Darenth Wood. Not common.

=Puccinia Scrophulariæ=, Lib. FIGWORT BRAND; spots pallid; sori
subrotund, oblong, or linear and confluent, surrounded by the ruptured
epidermis; spores very much crowded, subglobose or oval, brownish,
plicate, but not truly septate; pedicels elongated.—On _Scrophularia
aquatica_. Penzance. Very rare.

=Puccinia Betonicæ=, DC. BETONY BRAND; spots obliterated; sori
hypogenous, subrotund, aggregate, surrounded by the ruptured epidermis;
spores very pale-brown, short, obovate, elliptic; peduncles short.—On
_Stachys Betonica_. Rare.

=Puccinia Vincæ=, Berk. PERIWINKLE BRAND; spots yellowish; sori
hypogenous, scattered, subrotund, surrounded by the ruptured epidermis;
spores brown, oblong, slightly constricted, lower cell rather
attenuated; peduncle very short.—On leaves of _Vinca major_. (Plate VI.
fig. 132.) Autumn. Not uncommon.

=Puccinia Campanulæ=, Carm. CAMPANULA BRAND; spots apparently none; sori
large, irregular, crowded, for a long time covered with the epidermis,
at length surrounded by it; spores oblong-ovate, or slightly
constricted; peduncles very short.—On _Campanulæ_. Not common.

=Puccinia clandestina=, Carm. SCABIOUS BRAND; spots yellowish; sori very
minute, distinct, but collected together in great numbers, dark brown;
epidermis evanescent; spores oblong, very slightly constricted,
pedunculate.—On _Scabiosa succisa_. Not common.

=Puccinia Compositarum=, Sch. COMPOSITÆ BRAND; spots obliterated or
whitish; sori small, subrotund, generally hypogenous, encircled with the
ruptured epidermis; spores brown, oval, scarcely constricted.—On the
leaves of _Centaureæ_, &c. Autumn. Common. (Plate IV. figs. 67, 68.)

=Puccinia Syngenesiarum=, Lk. THISTLE BRAND; spots obliterated; sori
minute, collected in oval blackish-brown, raised spots, covered with the
epidermis; spores brown; peduncles very short.—On the leaves of
Thistles. Autumn. Common. (Plate IV. figs. 63, 64.)

=Puccinia glomerata=, Grev. RAGWORT BRAND; spots pale; sori roundish,
depressed, often confluent; spores oblong, very variable; peduncles
short.—On leaves of Ragwort, _Senecio Jacobæa_. Not common.

=Puccinia variabilis=, Grev. VARIABLE BRAND; sori amphigenous, minute,
roundish, surrounded by the ruptured epidermis, nearly black; spores
variable, obtuse, cells often subdivided; peduncle very short.—On leaves
of Dandelion. Summer and Autumn. Not uncommon. (Plate IV. figs. 82, 83.)

=Puccinia Valantiæ=, Pers. CROSSWORT BRAND; spots obliterated; sori
small, subrotund, scattered or crowded; spores pale-brown, obovate,
attenuated below, the upper segment globular, easily separating.—On
_Galium cruciatum_. Autumn. Not common.

=Puccinia Galiorum=, Lk. BEDSTRAW BRAND; spots obliterated; sori
hypogenous, partly covered with and surrounded by the ruptured
epidermis, scattered; spores brown.—On the leaves of several species of
_Galium_ and _Asperula odorata_. Not uncommon. (Plate VIII. figs. 172,
173.)

=Puccinia Umbelliferarum=, DC. PIG-NUT BRAND; spots obliterated; sori
small and scattered, subrotund, surrounded by the remains of the
ruptured epidermis; spores brown, broadly elliptic, much constricted;
peduncle short.—On various _Umbelliferæ_. Common. (Plate IV. figs. 71,
72.)

=Puccinia Ægopodii=, Lk. GOUTWEED BRAND; spots brown; sori minute,
subrotund and elongated, surrounded by the ruptured epidermis, often
circinating, and forming roundish patches; spores brown; peduncles very
short.—On _Ægopodium podagraria_.

=Puccinia Saniculæ=, Grev. SANICLE BRAND; orbicular, variable in size,
blackish-brown, scattered, rather confluent; spores very obtuse;
peduncles somewhat elongated.—On _Sanicula Europæa_. Not uncommon.
Summer and Autumn.

=Puccinia bullaria=, Lk. HEMLOCK BRAND; spots obliterated; sori
subrotund or oblong, covered with the epidermis; spores brown, peduncle
short, nearly obsolete.—On dry stems of _Conium maculatum_ and other
_Umbelliferæ_. August and Sept.

=Puccinia Smyrnii=, Cd. ALEXANDER’S BRAND; spots obliterated; sori
hypogenous, large, solitary, scattered, brown; spores ovoid, obtuse,
verrucose, slightly constricted, minutely pedicellate.—On _Smyrnium
olusatrum_. (Plate III. figs. 55, 56.)

=Puccinia Anemones=, Pers. ANEMONE BRAND; spots obliterated; sori
subrotund, surrounded by the ruptured epidermis, scattered, aggregate,
and confluent; spores brown, very much constricted, consisting of two
nearly globose portions, echinulate; peduncles very short.—On various
species of _Anemone_. Very common on _Anemone nemorosa_. April and May.
(Plate IV. figs. 64, 65.)

=Puccinia Calthæ=, Lk. MARSH-MARIGOLD BRAND; spots brownish; sori small,
subrotund, convex, surrounded by the ruptured epidermis, scattered;
spores obovate, attenuated below, slightly constricted; peduncle very
short.—On leaves of Marsh Marigold. Spring. Rare.

=Puccinia Noli-tangeris=, Corda. BALSAM BRAND; spots irregular,
confluent, brownish; sori gregarious, reddish-brown; spores oblong,
obtuse or attenuated, distinctly apiculate, brown; peduncles
rudimentary. On leaves of _Impatiens noli-tangere_. Gathered at Albury,
Surrey, by the Rev. L. Jenyns.—(_M. J. B._)

=Puccinia Violarum=, Lk. VIOLET BRAND; spots yellowish; sori hypogenous,
small, crowded, covered with the epidermis, then surrounded by it;
spores brown, elliptic or broadly elliptic, slightly constricted.—On
Violets. Autumn. Common.

=Puccinia Lychnidearum=, Lk. LYCHNIS BRAND; spots yellowish; sori
subrotund or oblong, unequal, scattered, rarely confluent; spores white,
at length brown, elongated, oblong, slightly constricted.—On leaves and
stems of _Lychnidæ_, _Sagina procumbens_. Autumn. Common.

=Puccinia umbilici=, Guep. PENNY-WORT BRAND; seated on pallid spots;
sori round, convex, compact, at length confluent in large orbicular
patches; spores subglobose, not constricted, shortly pedicellate.—On
_Cotyledon umbilicus_. Penzance, Guernsey, Corwen, N. Wales. _W.
Pamplin._ (Plate IV. figs. 80, 81.)

=Puccinia Rhodiolæ=, B. and Br. STONECROP BRAND; spots orbicular, brown;
sori minute, crowded; spores shortly pedicellate, articulations
depressed, sometimes spuriously subdivided.—On leaves of _Sedum
Rhodiola_. Summer. Not common.

=Puccinia Saxifragarum=, Schl. MOSCHATEL BRAND; spots obliterated; sori
subrotund, scattered, crowded and confluent, when young surrounded by
the epidermis; spores red-brown, rather short, oblong, slightly
constricted.—On both surfaces of the leaves of _Adoxa moschatellina_.
Not uncommon. Summer.

=Puccinia Chrysosplenii=, Grey. GOLDEN-SAXIFRAGE BRAND; sori of various
sizes, few together and confluent, pale brown; spores long, somewhat
waved, much attenuated at either extremity; peduncle elongated.—On the
under surface of the leaves of _Chrysosplenium oppositifolium_. Rare.

=Puccinia Epilobii=, DC. WILLOW-HERB BRAND; spots pale; sori hypogenous,
subrotund, crowded; epidermis evanescent; spores effuse, cinnamon,
broadly elliptic, strongly constricted; peduncles very short.—On the
leaves of _Epilobium palustre_. Not common.

=Puccinia pulverulenta=, Grev. GREAT WILLOW-HERB BRAND; sori hypogenous,
dark brown, scattered or subconfluent, open concentric; spores minute,
obovate, slightly constricted, lower cell rather attenuated; peduncle
not very short.—On the leaves of _Epilobium montanum_ and _E. hirsutum_.
August and September. Common. (Plate IV. figs. 78, 79.)

=Puccinia Circææ=, Pers. NIGHTSHADE BRAND; spots obliterated; sori
minute, semiglobose, crowded into subrotund patches, occasionally
confluent, generally covered with the epidermis; spores brown, oblong,
often acute, sometimes obtuse; peduncles long, thick.—On the leaves of
_Circæa lutetiana_ and _C. alpina_. Autumn. Not common.

=Puccinia Prunorum=, Lk. PLUM-TREE BRAND; spots obliterated; sori
hypogenous, subrotund scattered, epidermis obliterated; spores brown,
peduncles very short.—On the leaves of Plum-trees. September and
October. Very common.

=Puccinia Fabæ=, Lk. BEAN BRAND; spots none; sori subrotund, or
elongated, surrounded by the ruptured epidermis; spores at length black,
ovato-globose; peduncle slender.—On Beans. August and September. Not
uncommon.

=Puccinia Buxi=, DC. BOX BRAND; spots none; sori subrotund, convex,
scattered; spores brown, oblong, rather strongly constricted, lower cell
slightly attenuated; peduncle very long.—On both surfaces of Box-leaves.
April and May. Not uncommon.


                          GYMNOSPORANGIUM, DC.

  Peduncles extremely long, agglutinated by gelatine into a tremelloid
        expanded mass. Spores uniseptate.

=Gymnosporangium Juniperi=, Lk.; forming a soft gelatinous, irregular,
orange mass; spores ovate or subelliptic, filled with subglobose
granules.—On living twigs of _Juniperus communis_.


                            PODISOMA, _Lk._

  Peduncles extremely long, agglutinated by gelatine into a common stem,
        spreading out above into a _clavariæform_ mass; spores mostly
        uniseptate.—_Berk. Outl._, p. 331.

=Podisoma Juniperi=, Fr.; orange, clavariæform, somewhat branched;
stroma simple; spores very long, lanceolate, filled with elliptic
granules.—On living branches of _Juniperus communis_. Not common.

=Podisoma foliicolum=, B.; epiphyllous, brown-black masses, subglobose,
subelliptic, or irregular, consisting of radiating, crowded, very
slender, agglutinated filaments, each bearing an elliptic or clavate,
very obtuse spore, 3- to 5-septate.—On living leaves of _Juniperus
communis_. Rare.

=Podisoma Sabinæ=, Fr.; red-brown, tuberculiform and clavate, simple;
stroma obliterated; spores obovate, uniseptate.—On living branches of
_Juniperus Sabinæ_. April. Not uncommon.


                              =CÆOMACEI=.

        Simple and free.
          Without appendages,
            Springing from delicate threads.   _Tilletia_.
            Produced in separate cells.—
                Deeply seated, pulverulent,  } _Ustilago_
                  generally nearly black     }
                Superficial, yellow or brown   _Uredo_.
            Not enclosed in separate cells     _Lecythea_.
          With appendages,
                Deciduous                      _Trichobasis_.
                Permanent                      _Uromyces_.
        Compound.
                Irregular                      _Polycystis_.
                Subglobose or shell-shaped     _Tuburcinia_.

    Spores of two orders—
                1. Spherical                 } _Coleosporium_.
                2. Cylindrical, septate      }
                1. Spherical                 } _Melampsora_.
                2. Wedge-shaped, compact     }
                1.  Concatenate, exposed     } _Cystopus_.
                2. Spherical, concealed      }


                            TILLETIA, _Tul._

  Spores spherical, reticulated, proceeding from delicate branched
        threads.

=Tilletia caries=, Tul. BUNT; included within the germen; spores
spherical, rather large, black.—On wheat, filling the grains with
dark-coloured spores, fetid when crushed. Autumn. Very common. (Plate V.
figs. 84-91.)


                           USTILAGO, _Link._

  Plant deeply seated. Spores simple, springing from delicate threads,
        or in closely-packed cells, ultimately breaking up into a
        powdery mass.—_Berk. Outl._, p. 335.

_Ustilago segetum_, Ditm. CORN SMUT; produced on the receptacle and
rachis; epidermis soon ruptured; spores loose, minute, globose,
black.—On the ears of corn and grasses. Autumn. Very common. (Plate V.
figs. 98, 99.)

=Ustilago urceolorum=, Tul. SEDGE SMUT; produced on the glumes and
utricles; epidermis soon bursting; spores in a compact mass, afterwards
breaking up, globose, rather large, granulated.—Surrounding the seed of
various _Carices_; as, _Carex prœcox_, _stellulata_, _recurva_, and
_pseudo-cyperus_. Autumn. Not uncommon. (Plate VI. figs. 109-111.)

=Ustilago longissima=, Tul. ELONGATED SMUT; produced on the leaves in
linear, long, parallel, dirty-olive patches; epidermis bursting
longitudinally; spores globose, breaking up into minute granules,
olive-black.—On leaves of _Poa aquatica_ and _fluitans_. Summer. Common.
(Plate V. figs. 105-107.)

=Ustilago olivacea=, Tul. OLIVE SMUT; infesting the enlarged receptacle;
epidermis soon bursting; spores olive-green, powdery, minute, mixed with
filaments.—On _Carex riparia_. Not common. (Plate VI. figs. 126, 127.)

=Ustilago hypodytes=, Fr. GRASS-CULM SMUT; produced on the culms beneath
the sheaths, afterwards exposed; spores minute, subglobose,
brownish-black.—On the culms of various Grasses. Summer. Sometimes not
uncommon. (Plate V. figs. 100, 101.)

=Ustilago Maydis=, Corda. MAIZE SMUT; produced on the stems, germens,
&c.; epidermis at length bursting; spores spherical, minute,
brownish-black, surface covered with echinulate warts.—On stems, &c., of
_Zea mays_. (Plate V. fig. 108.)

=Ustilago Montagnei=, Tul. BEAKSEDGE SMUT; produced on the seeds;
epidermis bursting; spores slightly angular, small, dark-coloured,
intermixed sparingly with fragile filaments.—On seeds of _Rhyncospora
alba_. Not common. (Plate V. figs. 96, 97.)

=Ustilago typhoides=, B. and Br. REED SMUT; prodded on the stems of
reeds, forming thick bullate patches several inches long, occupying
whole internodes, covered by their sheath; spores globose, rather
large.—On stems of _Arundo phragmitis_. Autumn. Not uncommon. (Plate VI.
figs. 128, 129.)

=Ustilago Salveii=, B. and Br. COCKSFOOT SMUT; produced on the leaves,
forming elongated parallel sori on the upper surface; spores obovate,
rather large, rough with minute granules.—On leaves of _Dactylis
glomerata_ and other Grasses. Not common. (Plate VI. figs. 117-119.)

=Ustilago grammica=, B. and Br. BANDED SMUT; forming little transverse
bands consisting of short parallel black lines, 1/12 of an inch or more
in length; spores globose, very minute.—On stems of _Aira aquatica_ and
_A. cæspitosa_. Uncommon. (Plate VI. figs. 120-122.)

=Ustilago vinosa=, Tul. OXYRIA SMUT; produced on the swollen
receptacles; spores roundish, very small, and minutely papillose,
separately pellucid, in clusters, violaceous.—On the receptacles of
_Oxyria reniformis_. Uncommon.

=Ustilago utriculosa=, Tul. UTRICLE SMUT; produced in the germen and
perigonium; epidermis soon ruptured; spores effuse, minute, globose,
purple-black.—On _Polygonum hydropiper_ and other _Polygona_. Autumn.
Not uncommon. (Plate VI. figs. 112-116.)

=Ustilago flosculorum=, Fr. FLORET SMUT; produced within the florets;
spores minute, purplish-brown.—On the florets of _Scabiosa arvensis_.
Not common. (Plate VI. figs. 123-125.)

=Ustilago receptaculorum=, Fr. GOATSBEARD SMUT; produced within the
receptacles; spores ovate, minute, reticulated, violet-brown, nearly
black, very profuse, filling the receptacle.—On the receptacles of
Goatsbeard. June, July. Common. (Plate V. figs. 92-95.)

=Ustilago antherarum=, Fr. ANTHER SMUT; produced on the anthers and
germens; spores subglobose, effuse, violet.—On the anthers of _Silene
inflata_, &c. (Plate V. figs. 102-104.)


                             UREDO, _Lév._

  _Stroma_ composed of little irregular cells forming a lentiform disk,
        whose surface is covered with many layers of cells, each of
        which encloses a spore; _spores_ simple, always without any
        appendage.—_Berk. Outl._, p. 331.

                                -------

                    * _Spores more or less yellow._

=Uredo Potentillarum=, DC. POTENTILLA UREDO; spots yellowish; sori
subrotund and oval, bullate, aggregate, open, confluent; spores
subglobose, subcoherent, orange.—On various _Rosaceæ_. Common.

=Uredo Saxifragarum=, DC. SAXIFRAGE UREDO; spots pallid; sori subrotund
and oval, raised, scattered and aggregate on the under surface;
epidermis ruptured, persistent; spores subglobose, yellow.—On various
_Saxifrages_.

=Uredo Filicum=, Desm. FERN UREDO; spots yellowish; sori subrotund,
bullate, scattered and aggregate on the under surface; epidermis at
length bursting; spores subglobose, yellow.—On Ferns (_Cystopteris_,
&c.) Not common.

=Uredo pustulata=, P. WILLOW-HERB UREDO; spots yellowish; sori
subrotund, minute, closed, scattered and confluent on both surfaces;
spores globose, yellow.—On _Epilobium palustre_.

=Uredo Hypericorum=, DC. ST. JOHN’S-WORT UREDO; spots yellowish; sori
subrotund, small, bullate, distinct, scattered on the under surface;
epidermis at length bursting; spores subglobose, cohering, orange.—On
various _Hyperica_. August. Not uncommon. (Plate VIII. figs. 174, 175.)

=Uredo Caryophyllacearum=, Johnst. STITCHWORT UREDO; spots yellowish;
sori subglobose, scattered and aggregate, minute, generally on the under
surface; epidermis closed; spores oval, at length yellow.—On various
_Caryophyllaceæ_. Autumn.

=Uredo Quercus=, Brond. OAK-LEAF UREDO; on the under surface; sori
yellow, then orange, minute, ovate, and orbicular, slightly prominent,
scattered, solitary or agglomerated into minute patches, surrounded by
the ruptured epidermis; spores subglobose, pellucid, not cohering.—On
Oak-leaves. September. Not common.

=Uredo porphyrogenita=, Kze. BIRD-CHERRY UREDO; spots purplish; sori
subrotund, small, aggregate, hypogenous; epidermis at length ruptured;
spores coherent, subglobose.—On leaves of _Prunus Padus_. Scotland,
1863. (_Rev. M. J. Berkeley._)

=Uredo Vacciniorum=, P. BILBERRY UREDO; spots yellow-brown; sori
subrotund, minute, aggregate, and scattered, on the under surface of the
leaves; epidermis seldom ruptured; spores ovoid, yellowish.—On
_Vaccinium Myrtillus_ and _V. vitis-idæa_. Scotland.

=Uredo confluens=, DC. MERCURY UREDO; on the under surface, depressed,
yellow, oblong, concentric, at length confluent; spores nearly oval.—On
_Mercurialis perennis_ and _M. annua_. May, June. Common. (Plate VII.
figs. 133, 134.)

=Uredo Alliorum=, DC. GARLIC UREDO; spots obliterated; sori linear,
oblong, and oval, on both surfaces; spores ovoid or subglobose, yellow
or whitish.—On various species of _Allium_. Common.


                          * * _Spores brown._

  =Uredo Statices=, Desm. SEA-LAVENDER UREDO; sori few and scattered,
        orbicular or oval; spores sessile, globose, brown.—On various
        species of _Statice_.

=Uredo Circææ=, A. & S. NIGHTSHADE UREDO; sori minute, crowded,
subrotund, slightly confluent, on the under surface; spores irregular,
ovate, small, ochraceous.—On leaves of _Circæa lutetiana_. June, July.
Common. (Plate VII. figs. 135, 136.)

=Uredo bifrons=, Grev. TWIN-FACED UREDO. On both surfaces of the leaves,
often opposite, scattered, round, light brown, girt with the remains of
the epidermis; spores globose.—On Sorrel leaves (_Rumex acetosa_ and _R.
acetosella_). July, September. Common. (Plate VII. figs. 137-139)


                            LECYTHEA, _Lév._

  _Stroma_ surrounded or sprinkled with elongated abortive spores.
        _Spores_ free, invested with their mother-cell, or
        concatenate.—_Berk. Outl._, p. 334.


                            * _Spores free._

=Lecythea Ruborum=, Lév. BRAMBLE RUST. Spots pale, brown or purple on
the opposite side, sometimes depressed above; sori subrotund, aggregate;
epidermis soon bursting; spores globose or subglobose, echinulate,
bright ochraceous-yellow.—On the under surface of Bramble leaves. July
and August. Very common. (Plate II. fig. 40.)

=Lecythea Rosæ=, Lév. ROSE RUST; spots yellow, small, scattered; spores
sub-oval, sometimes minutely pedicellate, orange.—On Rose-leaves. July,
September. Extremely common. (Plate II. fig. 37.)

=Lecythea Poterii=, Lév. BURNET RUST; spots obliterated, rufous on the
opposite side; sori subrotund, scattered, minute on the under surface;
epidermis bursting; spores subglobose, often pedicellate, intense
orange; barren spores pale, cylindrical, and slightly curved.—On
_Poterium Sanguisorba_. Summer. Common. (Plate III. fig. 31.)

=Lecythea Populina=, Lév. POPLAR RUST; hypogenous; sori yellow, roundish
or oblong, surrounded by the ruptured epidermis; spores copious,
elongated or ovate.—On Poplar and Birch leaves. Summer. Common.

=Lecythea Euphorbiæ=, Lév. SPURGE RUST; spots obliterated; sori
subrotund, small, scattered, surrounded by the ruptured epidermis;
barren spores pyriform or subglobose, pedicellate; fertile spores
subglobose, orange.—On the under surface of the leaves of various
species of _Euphorbia_, especially _E. helioscopia_ and _E. peplus_.
August. Very common.

=Lecythea epitea=, Lév. TAWNY WILLOW RUST; sori roundish, scattered, at
first tawny, at length growing pale, surrounded by the ruptured
epidermis; spores subrotund and pyriform.—On the under surface of
Willow-leaves.

=Lecythea mixta=, Lév. ORANGE WILLOW RUST; spots yellow; sori subrotund,
aggregate, confluent, effuse, permanently surrounded by the ruptured
epidermis; spores oblong and pyriform, orange.—On both surfaces of the
leaves of Willows.

=Lecythea Saliceti=, Lév. COMMON WILLOW RUST; spots yellowish; sori
subrotund, solitary, or in circles, surrounded by the ruptured
epidermis; barren spores subglobose and pedicellate or pyriform; fertile
spores subglobose, orange.—On the under surface of Willow-leaves.
Autumn. Common.

=Lecythea Baryi=, Berk. DE BARY’S RUST; sori few; cystidia with an
abrupt globose head; spores subglobose.—On leaves of _Brachypodium
pennatum_. Very rare.

=Lecythea Valerianæ=, Berk. VALERIAN RUST; spots yellowish; sori
subrotund, small, confluent, sometimes circinating; epidermis at length
bursting; spores reddish-brown, subglobose or clavate, shortly
pedicellate.—On _Valeriana officinalis_. August.


                         * * _Spores invested._

=Lecythea gyrosa=, Berk. RINGED RUST; spots obliterated; sori minute,
confluent, and forming a small distinct ring; epidermis bursting; spores
globose and elongato-pyriform, yellow or pale.—On the upper surface of
Raspberry and Bramble leaves, forming a more or less perfect ring with
the centre unoccupied. September. (Plate VIII. figs. 162-164.)


                      * * * _Spores concatenate._

=Lecythea Capræarum=, Berk. SALLOW RUST; spots obliterated, yellow on
the opposite side; sori varied in form, here and there confluent,
surrounded by the ruptured epidermis; barren spores subglobose and
pyriform, pedicellate; fertile spores subglobose, dirty yellow.—On the
under surface of the leaves of Sallows. June to August. Very common.
(Plate VIII. figs. 160, 161.)

=Lecythea Lini=, Berk. FLAX RUST; spots yellowish; sori subrotund,
scattered, surrounded by the ruptured epidermis; spores globose or
pyriform, sometimes pedicellate.—On _Linum catharticum_. July. Not
uncommon. (Plate VIII. figs. 165-167.)


                          TRICHOBASIS, _Lév._

  _Spores_ free; attached at first to a short peduncle, which at length
        falls away.—_Berk. Outl._, pp. 332.


                           * _Spores yellow._

=Trichobasis rubigo-vera=, Lév. ROUND CORN RUST; spots yellow, heaps
oval, scattered, generally on the upper surface; epidermis at length
bursting longitudinally; spores subglobose, reddish-brown, easily
dispersed.—On Grasses and Corn. Throughout the Summer. Very common.
(Plate VII. figs. 140-142.)

=Trichobasis linearis=, Lév. LONG CORN RUST; spots yellow-brown. Sori
elliptic, then elongated and linear; epidermis bursting; spores oblong
or globose, yellow.—On leaves and sheaths of Corn and Grasses. Summer.
Common. Plate VII. figs. 143, 144.)

=Trichobasis Glumarum=, Lév. GLUME RUST; sori minute, round, scarcely
convex, subgregarious, often confluent. Spores globose or subovoid,
orange, not pedicellate; epispore smooth.—On the glumes of Cereals.
August.

=Trichobasis Symphyti=, Lév. COMFREY RUST; Sori minute, very numerous,
scattered, roundish, then confluent; epidermis ruptured, scarcely
conspicuous around the margin; spores subglobose, pallid orange.—On
Comfrey.

=Trichobasis Pyrolæ=, B. WINTERGREEN RUST; spots yellowish-brown on the
opposite side; sori globose, minute, scattered or aggregate, on the
under surface; epidermis generally closed; spores subglobose, yellow.—On
_Pyrola rotundifolia_, &c.

=Trichobasis Petroselini=, B. PARSLEY RUST; spots yellowish; sori
subrotund and oval, confluent, on both surfaces; epidermis at length
ruptured; spores globose or subglobose, occasionally obsoletely
pedicellate, pale yellow.—On various _Umbelliferæ_.

=Trichobasis Senecionis=, B. GROUNDSEL RUST; spots obliterated; sori
solitary or regularly crowded, subrotund and oval, on the under surface,
surrounded by the ruptured epidermis; spores subglobose, orange.—On
various species of Groundsel. July. Very common. Plate VII. figs. 145,
146.)

=Trichobasis Caricina=, B. SEDGE RUST; spots red; sori oval, minute,
scattered, surrounded by the ruptured epidermis; spores subglobose,
reddish, then brown.—On _Carex pendula_, _C. pseudo-cyperus_, &c. June
to August. Common. (Plate VIII. figs. 170, 171.)


                          * * _Spores brown._

=Trichobasis oblongata=, B. LUZULA RUST; spots oblong, often confluent,
yellow-brown; sori elliptic, on both surfaces; epidermis closed; spores
brown, obtuse at either extremity.—On _Luzulæ_. May to July. (Plate VII.
figs. 158, 159.)

=Trichobasis Scillarum=, B. HYACINTH RUST; spots oblong or subrotund,
crowded into patches; epidermis bursting longitudinally; spores
rubiginous, obovate, shortly pedunculate.—On the Wild Hyacinth, &c.

=Trichobasis Cichoracearum=, Lév. HAWKWEED RUST; on both sides of the
leaf, dark, fuscous, minute, round, scattered: spores globose, rarely
minutely pedicellate.—On Thistles and Hawkweed. July to September.
Common.

=Trichobasis Artemisiæ=, B. MUGWORT RUST; spots obliterated, brownish on
the opposite side; sori subglobose and oval, minute, scattered, on both
surfaces; epidermis soon ruptured; spores subglobose, brownish.—On
_Artemisia vulgaris_, &c. Not common.

=Trichobasis Labiatarum=, Lév. MINT RUST; spots yellowish and brown;
sori subrotund, scattered, subaggregate, on the under surface; epidermis
ruptured; spores subglobose, brown.—On various _Labiatæ_. August to
September. Common.

=Trichobasis Lychnidearum=, Lév. CHICKWEED RUST; spots pallid yellowish;
sori subrotund plane, scattered on the under surface, cinnamon, at
length brownish; epidermis ruptured; spores globoso-ovoid, sessile, or
shortly pedicellate.—On _Caryophyllaceæ_. Summer and Autumn.

=Trichobasis Umbellatarum=, Lév. HEMLOCK RUST; spots yellowish; sori
subrotund and ovate, scattered, on the under surface, surrounded by the
ruptured epidermis; spores ovate, oval, and oblong in the same heap,
brown.—On _Conium maculatum_, _Apium graveolens_, and other
_Umbelliferæ_. August and September.

=Trichobasis Heraclei=, B. HOGWEED RUST; on the under surface,
scattered, sometimes subconfluent, roundish, light brown, girt by the
remains of the epidermis; spores obovate, with a very short peduncle.—On
_Heracleum spondylium_. June and July.

=Trichobasis Hydrocotyles=, Cooke. FLUKEWORT RUST; without definite
spots; sori chiefly on the upper, sometimes on the under surface,
scattered, variable, roundish, erumpent, surrounded by the ruptured
epidermis; spores subglobose, at length brown; epispore rough with
minute tubercles.—On _Hydrocotyle vulgaris_. Epping, July to September,
1863 and 1864. (Plate VIII. figs. 168, 169.)

=Trichobasis Betæ=, Lév. BEET-LEAF RUST; spots yellow; heaps subrotund
and oval, scattered and concentric, on the upper surface; epidermis at
length bursting; spores subglobose, shortly pedicellate, brown.—On the
leaves of Beet. August and September. Common.

=Trichobasis Fabæ=, Lév. BEAN RUST; spots obliterated; sori subrotund
and oval; bullate, scattered and aggregate, surrounded by the ruptured
epidermis; spores ovoid, brown.—On Beans. August and September. Common.

=Trichobasis Galii=, Lév. BEDSTRAW RUST; spots yellowish; sori
subrotund, aggregate, closed; spores globose, reddish.—On _Galium
verum_, _saxatile_, &c. July and August.

=Trichobasis suaveolens=, Lév. THISTLE RUST; spots obliterated, yellow
on the opposite side; sori subrotund, nearly plane, scattered, at length
confluent, on the under surface, surrounded by the ruptured epidermis;
spores globose, brown.—On leaves of Thistles, frequently covering the
whole under surface. Summer. Common. (Plate VII. figs. 151-153.)

=Trichobasis Polygonorum=, B. KNOTGRASS RUST; spots red-yellow, widely
effused; sori subrotund, scattered, sometimes forming a ring, epidermis
at length bursting; spores somewhat obovate, brown.—On _Polygonum
aviculare_, _amphibium_, and other species. July to September. Common.

=Trichobasis Vincæ=, B. PERIWINKLE RUST; spots yellowish; sori small,
subrotund, and oval, on the under surface, surrounded by the ruptured
epidermis; spores oval, rather ovoid, brown.—On leaves of _Vinca major_.
May and June. (Plate VI. fig. 130, 131.)

=Trichobasis Geranii=, B. GERANIUM RUST; spots yellowish; sori
subrotund, nearly plane, scattered or confluent; spores subglobose,
brown.—On various species of Geranium.

=Trichobasis Violarum=, B. VIOLET RUST; spots yellowish; sori subrotund,
scattered, generally on the under surface; epidermis ruptured,
persistent; spores subglobose, brown.—On leaves and petioles of Violets.
July. Not uncommon.

=Trichobasis Parnassiæ=, Cooke. GRASS OF PARNASSUS RUST; on both
surfaces of the leaves; sori at first bullate, at length rupturing the
epidermis, scattered, often confluent; spores globose or nearly so,
rather large, tawny brown.—On _Parnassia palustris_. Irstead, Norfolk.
September, 1864.

=Trichobasis Epilobii=, Berk. WILLOW-HERB RUST; spots yellowish; sori
subrotund, scattered, surrounded by the ruptured epidermis, often on the
under surface; spores subglobose, brown.—On _Epilobium montanum_, &c.
June and July.

=Trichobasis Rhamni=, Cooke. BUCKTHORN RUST; seated on definite
yellowish spots; sori occurring only on the under surface of the leaves,
scattered or collected in clusters, very minute, roundish, or oblong;
spores at length rusty brown, subglobose.—On _Rhamnus catharticus_.
Selsdon, Surrey. September 16, 1864. (_A. Grugeon._)


                            UROMYCES, _Lév._

  _Spores_ unilocular, attached permanently to a decided peduncle of
        greater or less length.—_Berk. Outl._, p. 333.

=Uromyces Alliorum=, DC. GARLIC RUST; spots obliterated, sori linear,
oblong, or oval, amphigenous; spores subglobose, yellow.—On species of
_Allium_.

=Uromyces Ulmariæ=, Lév. GOLDEN RUST; broad, pulverulent, on the under
surface of leaves, nerves, and petioles; spores numerous, subglobose,
bright reddish-orange.—On _Spiræa Ulmariæ_, Roses, &c. Common. (Plate
VII. figs. 147, 148.)

=Uromyces appendiculata=, Lév. LONG-STEMMED RUST; spots yellowish-brown,
sori subrotund and oval, confluent, nearly plane, on the under surface.
Epidermis bursting, spores ovoid, brown, with a long peduncle.—On
_Leguminosæ_ and other plants. August and September. (Plate VII. figs.
149, 150.)

=Uromyces apiculosa.=, Lév. SHORT-STEMMED RUST: spots yellow or brown,
sori subrotund, scattered, surrounded by the ruptured epidermis; spores
ovoid, brown, shortly pedunculate.—On dock and various other plants.
August and September. Common. (Plate VII. figs. 154, 155.)

=Uromyces Limonii=, Lév. SEA-LAVENDER RUST; epiphyllous, sori bullate,
scattered or disposed in rings; spores ovate.—On _Statice limonia_.

=Uromyces Ficariæ=, Lév. PILEWORT RUST; spots yellowish, sori scattered,
aggregate, confluent, and expanded; epidermis ruptured; spores ovoid,
brown.—On _Ranunculus Ficaria_. May and June. Common. (Plate VII. figs.
156, 157.)

=Uromyces Primulæ=, Lév. PRIMROSE RUST; spots yellowish, sori subrotund
and oval, aggregate, on the under surface; epidermis at length bursting;
spores ovoid, brown.—On Primroses.

=Uromyces intrusa=, Lév. LADY’S-MANTLE RUST; on the under surface,
scattered, or partially aggregate, reddish-brown, rounded, somewhat
prominent, minute, very unequal; spores roundish or oval.—On _Alchemilla
vulgaris_.

=Uromyces Iridis=, Lév. IRIS RUST; on the under, rarely on the upper,
surface; spots yellow, sori small, pale red-brown, oblong and linear,
scattered or aggregate, scarcely convex; epidermis bullate, rarely
bursting longitudinally; spores globose or broadly elliptic, pale brown,
pellucid.—On _Iris fœtidissima_. August to September. Not uncommon.


                           POLYCYSTIS, _Lév._

  _Spores_ irregular, consisting of several cells.—_Berk. Outl._, p.
        334.

=Polycystis Colchici=, Tul. MEADOW-SAFFRON SMUT; sori elongated,
bursting irregularly; spores smooth or slightly papillose.—On leaves of
Meadow-Saffron. Not common.

=Polycystis Violæ=, B. and Br. VIOLET SMUT; sori scattered, elongated,
on both surfaces of the leaves and petioles; spores more or less
globose, consisting of several cells surrounded by a common irregular
crust.—On leaves and petioles of Violets. August. Common. (Plate IX.
figs. 185, 186.)

=Polycystis pompholygodes=, Lév. BUTTERCUP SMUT; sori varied in form,
bullate, epidermis inflated, at first entire, then bursting irregularly,
its remains surrounding the clusters; spores copious, subglobose, black,
opaque or pellucid.—On _Ranunculus repens_ and other _Ranunculaceæ_.
Summer. Very common. (Plate IX. figs. 183, 184.)

=Polycystis parallela=, B. and Br. RYE SMUT; sori very long, linear,
epidermis bursting longitudinally, spores globose, with several
projecting nodules, dark brown.—On culms and sheaths of Rye and on the
leaves of Carices. (Plate IX. figs. 187, 188.)


                           TUBURCINIA, _Fr._

  _Plant_ deeply seated; _spores_ multicellular, subglobose, or
        conchiform. _Berk. Outl._, p. 335.

=Tuburcinia scabies=, B. POTATO SMUT; spores globose composed of minute
cells forming together a hollow globe with one or more lacunæ, generally
attached laterally by a slender thread, olive. On Potatoes. Common.
(Plate III. fig. 54.)

=Tuburcinia Trientalis=, B. and Br. TRIENTALIS SMUT; sori two lines
broad, bullate, containing a black mass of rather irregular depressed
subglobose spores, which are very opaque and distinctly cellular.
Hyphasma white, branched, creeping, delicate.—On leaves of _Trientalis
Europæa_. August and September. Scotland. (Plate III. figs. 52, 53.)


                          COLEOSPORIUM, _Lév._

  _Spores_ cylindrical, septate, some separating at the joints, some of
        a different nature, persistent.—_Berk. Outl._, p. 333.

=Coleosporium Tussilaginis=, Lév. COLTSFOOT RUST; on the under surface,
prominent, crowded, generally forming circles, becoming very confluent;
spores numerous, sub-ovate, orange-yellow.—On _Tussilago Farfara_.
Summer. Common. (Plate VIII. figs. 180, 181.)

=Coleosporium pingue=, Lév. TAWNY ROSE RUST; spots obliterated, sori
effuse, on the nerves and petioles of the leaves; spores ovoid,
yellowish-brown.—On Roses, &c.

=Coleosporium Petasitis=, Lév. BUTTERBUR RUST; on the under surface,
minute, depressed, spreading, somewhat aggregate, subconfluent,
irregular in form; spores oval, orange, or orange-red.—On _Tussilago
Petasites_. Autumn. Common.

=Coleosporium Campanulæ=, Lév. CAMPANULA RUST; spots obliterated, brown
on the opposite side, sori irregular, confluent, plane, on the under
surface; spores subglobose, cohering, yellow, at length pale. On leaves
of various Campanulæ. September and October.

=Coleosporium Sonchi-arvensis=, Lév. SOW-THISTLE RUST; on the under
surface, depressed, irregular in form, scattered, partially confluent;
spores ovate, reddish orange.—On _Sonchus oleraceus_ and _arvensis_.
Summer. Common. (Plate VIII. figs. 178, 179.)

=Coleosporium Rhinanthacearum=, Lév. COW-WHEAT RUST; spots none or
subferruginous; sori irregular, confluent, on the under, rarely on both
surfaces; spores subglobose, compact, golden-yellow.—On _Euphrasia
officinalis_, _Bartsia odontites_, _Melampyrum arvense_, &c. August and
September. Common. (Plate VIII. figs. 170, 177.)


                          MELAMPSORA, _Cast_.

  Spores of two orders, crowded into a dense compact mass, with or
        without a covering, wedge-shaped. _Berk. Outl._, p. 333.

=Melampsora Euphorbiæ=, Cast. Hypophyllous; sori of summer spores
golden-yellow, scattered, distinct, sometimes cauline; spores small,
subglobose; sori of perfect spores becoming black, small, roundish,
spores prismatic, membrane thickened above, dark brown.—On leaves and
stems of _Euphorbia helioscopia_, _E. exigua_, and other species of
spurge. Common. (Plate IX. figs. 193, 194.)

=Melampsora Populina=, Lév. Hypophyllous, epiphyllous, or amphigenous,
at first yellow or orange; summer spores obovate-oblong, attenuated or
truncate, echinulate; paraphyses obovate, capitate or claviform,
abundant in fully-ripened sori; sori of perfect spores at first tawny
yellow, becoming black during the winter, swelling in the spring, and
becoming of a cinnamon-colour, hypophyllous, roundish, or oblong; spores
prism-shaped, 5-6 together, yellowish, smooth.—On leaves of _Populus
nigra_. Common. Spores perfected in February. (Plate IX. figs. 195,
196.)

=Melampsora Tremulæ=, Tul. Hypophyllous; sori of summer spores
punctiform, prominent, or papillæform, numerous; spores tawny-yellow,
elliptical or obovate; paraphyses slender; sori of perfect spores
scattered, at length blackish; spores elongated, compressed, attenuated
downwards, yellowish.—On leaves of _Populus tremula_. Common. Spores
perfected during the winter.

=Melampsora Betulina=, Desm. Hypophyllous; sori of summer spores bright
yellow or orange, oblong, cylindrical, or obovate, truncate at the base,
echinulate; paraphyses encircling or intermixed, obovate, smooth,
hyaline; sori of perfect spores confluent, of an obscure brown in the
winter, becoming of a bright orange when mature; spores elongated,
attenuated below, polygonal, ochraceous.—On leaves of _Betula alba_.
Common. Spores perfected in January and February. (Plate IX. figs. 189,
190.)

=Melampsora Salicina=, Lév. Epiphyllous or hypophyllous; sori, or heaps
of summer spores, scattered, pale orange, bright orange, or cinereous;
spores ovato-globose, paraphyses capitate, rarely obovate; sori of
perfect spores epiphyllous, scattered or aggregate, at first
yellowish-tawny, then brownish, at length nearly black, bullate; spores
oblong, closely packed, and laterally compressed.—On _Salix viminalis_
and _S. capræa_. Common. Spores perfected in February. (Plate IX. figs.
191, 192.)


                               CYSTOPUS.

  Receptacle consisting of thick branched threads; conidia concatenate,
    at length separating; oospores deeply seated on the mycelium.

=Cystopus candidus=, Lév. CRUCIFER WHITE RUST; conidia equal, globose;
membrane equal, ochraceous; oospores subglobose, epispore
yellowish-brown, with irregular obtuse warts; warts solid.—On
Shepherd’s-purse, Cabbages, and other Cruciferæ. Summer. Very common.
(Plate X. figs. 198-200, 205-207.)

=Cystopus cubicus=, Str. GOATSBEARD WHITE RUST; conidia unequal;
terminal cell sterile, larger than the rest; membrane thickened,
ochraceous, rarely yellowish; fertile cells shortly cylindrical;
membrane hyaline; oospores globose; epispore brown, verrucose; warts
hollow, round, or irregular.—On goatsbeard, salsify, and scorzonera.
Summer and autumn. Common. (Plate X. figs. 201, 202, 210.)

=Cystopus Lepigoni=, De By. SANDWORT WHITE RUST; conidia unequal;
terminal cell sterile, globose; membrane thickened; fertile cells
subglobose or cylindrical; membrane hyaline; oospores globose; epispore
brown, tubercles minute, irregular, very convex, often resembling
spines.—On _Spergutaria rubra_. Swanscombe Marshes, September, 1864.
(_R. G. Keeley._)


                          PERONOSPOREI, De By.

                          PERONOSPORA, _Casp._

  Parasitic threads mostly inarticulate. Spores of two kinds:—1.
    Acrospores on the tips of the branchlets; 2. Oospores large,
    globose, on the creeping mycelium.

=Peronospora infestans=, Mont. POTATO MOULD; threads of mycelium
slender, always destitute of suckers; fertile threads thin, gradually
attenuated upwards, with one to five branches, one or more inflated
vesicles near the apices of the branches; branches either simple or with
short branchlets; acrospores ellipsoid or ovoid; apex furnished with a
prominent papilla.—On leaves, stems, and tubers of the Potato, causing
the potato-murrain. Very common since 1845. (Plate XIV. fig. 264.)

=Peronospora nivea=, Ung. (_P. macrospora_, B.). PARSNIP MOULD; threads
of mycelium stout, often torulose; suckers numerous, vesicular, obovate;
fertile threads fasciculate, dwarfish, tapering or subulate, or once or
twice shortly bifurcate, rarely trifurcate, with one to four horizontal
branches near the summit, once, twice, or three times bifurcate;
acrospores subglobose or ovoid, with an obtuse papilla at the apex.—On
various _Umbelliferæ_. Common and variable.

=Peronospora pygmæa=, Ung. (_P. curta_, Berk.). ANEMONE MOULD; threads
of mycelium thickened, often constricted and varicose; suckers minute,
obovate, or pear-shaped; fertile threads fasciculate (2-5 or more),
simple above or divided at the apex into 2-4 short simple branches, or
shortly twice dichotomous, or all simple, obtuse, surmounted by 2-4
short spicules; acrospores ovoid or ellipsoid, variable in size; apices
broadly and obtusely papillate.—On Wood-anemone. Not uncommon. (Plate
XV. fig. 267.)

=Peronospora gangliformis=, Berk. LETTUCE MOULD; threads of the mycelium
stout, now and then torulose; suckers vesicular, obovate or clavate;
fertile threads 2-6 times dichotomous, sometimes trichotomous; stems and
primary branches slender, dilated or inflated above; the ultimate ramuli
inflated at the apex into a turbinate or subglobose vesicle bearing from
2-8 subulate processes or spicules; acrospores minute, subglobose;
apices with broad depressed papillæ, produced on the spicular processes,
On Lettuces and other _Compositæ_. Frequent. (Plate XIV. fig. 265.)

=Peronospora parasitica=, Pers. CABBAGE MOULD; threads of the mycelium
thickened and much branched; suckers numerous, branched; branches
clavate, obtuse; fertile threads thick, soft, flexile, equal or unequal,
5-8 times dichotomous, rarely trichotomous; branches always repeatedly
trifurcate; acrospores broadly elliptical, very obtuse at the apex,
white.—On Cabbages, Shepherd’s-purse, and other Cruciferæ, sometimes in
company with _Cystopus candidus_. Summer and autumn. Common. (Plate
XIII. fig. 262.)

=Peronospora Viciæ=, Berk. PEA MOULD; fertile threads densely cæspitose,
erect, equal, rarely unequal, 6-7-8 times dichotomous; ultimate ramuli
shortly subulate, acute; acrospores ellipsoid, very obtuse at the apex,
obtuse or slightly acute at the base; membrane with a violaceous
tint.—On Tares, Peas, &c. Frequent. (Plate XV. fig. 266; Plate X. fig.
212.)

=Peronospora Arenariæ=, Berk. SANDWORT MOULD; fertile threads slender,
6-7 times equally, rarely unequally, dichotomous; branches spreading;
ultimate ramuli slender, acute, subulate, nearly erect; acrospores
broadly elliptical, oftentimes very obtuse, small; membrane scarcely
violaceous.—On _Arenaria serpyllifolia_ and _A. trinervis_.—June. (Plate
XVI. fig. 268; Plate X. fig. 211.)

=Peronospora effusa=, Grev. SPINACH MOULD; fertile threads fasciculate,
short, thick, 2-6, rarely 7 times dichotomous above; acrospores broadly
ellipsoid, sometimes very obtuse; membrane with a violaceous tint. On
Spinach, Goosefoot, and some other allied plants. Spring and autumn. Not
uncommon. (Plate X. figs. 214, 215.)

=Peronospora Urticæ=, Casp. NETTLE MOULD; fertile threads small, loosely
4-6 times dichotomous; branches flexuose, ultimate ramuli subulate,
arcuate, often deflexed; acrospores large, broadly ovoid or subglobose,
distinctly pedicellate; apices very obtuse; membrane violaceous.—On
leaves of the common Nettle.

=Peronospora trifoliorum=, De By. CLOVER MOULD; fertile threads
cæspitose, equally or unequally 6-7 times dichotomous, rarely
trichotomous; ultimate branches subulate, acute, slightly curved;
acrospores ellipsoid, very obtuse; membrane with a slightly violaceous
tint; oospores large; epispore brown.—On Lucern (_Medicago sativa_).
Highgate and Hampstead, 1864.

=Peronospora grisea=, Ung. VERONICA MOULD; fertile threads erect,
fasciculate, grey, 5-7 times regularly dichotomous; branches gradually
attenuated; primary oblique erect; others spreading, flexuose; ultimate
mostly unequal, slightly arcuate; acrospores ellipsoid or ovoid, obtuse;
membrane pale and dirty violet.—On leaves of _Veronica beccabunga_. May,
1846. (Plate X. fig. 213.)

=Peronospora arborescens=, Berk. POPPY MOULD; fertile threads slender,
erect, 7-10 times dichotomous above; branches more or less flexuose,
squarrose, spreading, gradually attenuated; ultimate ramuli shortly
subulate, more or less arcuate; acrospores very small, subglobose;
membrane scarcely violaceous.—On the Corn Poppy. June. Common.

=Peronospora Schleideniana=, De By. (_P. Destructor_, B.) ONION MOULD;
fertile threads robust, erect, not septate, branched alternately;
ultimate ramuli forked and uncinate or divaricate; acrospores seated on
the tips of the ultimate ramuli, obovoid or nearly pear-shaped,
attenuated at the base; membrane of a dirty violet-colour.—On the leaves
of various species of _Allium_. Often plentiful. (Plate XIII. fig. 263.)

=Peronospora violacea=, Berk. SCABIOUS MOULD; fertile threads branched;
acrospores sub-elliptical, violet-coloured. All that is known of this
species is contained in the following note from the Rev. M. J.
Berkeley:—“It grew on the petals of the common scabious. I have not
found it again, and have either lost or mislaid my specimens. You may
describe it as _læte violacea_; _floccis ramosis_; _sporis
subellipticis_, _violaceis_. It is probably the _Farinaria_ on Scabious
of Sowerby.” (M. J. B.)

=Peronospora sordida=, Berk. FIGWORT MOULD; forming broad, irregular,
dirty, pallid spots on the under surface of the leaves; fertile threads
loosely dichotomous above; tips forked, unequal; acrospores obovate,
apiculate.—On leaves of _Scrophularia_. Jedburgh.

=Peronospora sparsa=, Berk. ROSE MOULD; fertile threads scattered, by no
means torulose, ultimate branches scarcely uncinate, dichotomous, pallid
grey; acrospores sub-elliptical.—On the under side of rose-leaves in
conservatories.

=Peronospora obliqua=, Cooke. DOCK MOULD; threads of the mycelium
slender; fertile threads fasciculate, erect, simple, rarely bifurcate,
attenuated upwards; acrospores large, ellipsoid, attached obliquely near
the base.—On the under surface of dock leaves. Winter and spring.
Probably not uncommon. Brownish circular spots on the leaves indicate
the presence of this mould, which is so minute that it might otherwise
be overlooked. (Plate XVI. fig. 269.)


                              =Erysiphei=.

       _Conceptacle with one sporangium._
             Appendages floccose            _Sphærotheca_.

       _Conceptacle with many sporangia._
             Appendages needle-shaped, rigid     _Phyllactinia_.
             Appendages hooked                   _Uncinula_.
             Appendages dichotomous              _Microsphæria_.
             Appendages floccose                 _Erysiphe_.


                          SPHÆROTHECA, _Lév._

  Mycelium arachnoid; perithecia globose, containing a single globose
        sporangium; appendages numerous, floccose.—_Berk. Outl._, p.
        404.

=Sphærotheca pannosa=, Lév. ROSE BLIGHT; mycelium thickened, woolly,
felted, persistent; conceptacles minute, globose, scattered; appendages
floccose, white; sporangium many-spored.—On the branches, calyces,
petioles, and leaves of Roses. Very common. (Plate XI. figs. 217, 218.)

=Sphærotheca Castagnei=, Lév. HOP BLIGHT; on both surfaces; mycelium
effuse, web-like, commonly evanescent; conceptacles minute, scattered,
globose; appendages numerous, short, flexuose above; sporangium
many-spored.—On the leaves of the Hop, Meadow-sweet, and various other
plants. Common. (Plate XI. fig. 216.)


                          PHYLLACTINIA, _Lév._

  Perithecia hemispherical, at length depressed, seated on a persistent
        or evanescent membranaceo-granular receptacle; appendages
        straight, rigid, acicular, at length bent back.—_Berk. Outl._,
        p. 404.

=Phyllactinia guttata=, Lév. HAZEL BLIGHT; amphigenous; mycelium
web-like, often evanescent; conceptacles large, scattered,
hemispherical, at length depressed; appendages hyaline, rigid, simple;
sporangia 4-20, containing 2-4 spores.—On the leaves of Hawthorn, Hazel,
Ash, Elm, Alder, Beech, Birch, Oak, Hornbeam, and various other plants.
Common. (Plate XI. figs. 219, 220.)


                            UNCINULA, _Lév._

  Mycelium floccose; perithecia globose; appendages rigid, simple, bifid
        or dichotomous, uncinate, at length bent upwards.—_Berk. Outl._,
        p. 404.

=Uncinula adunca=, Lév. WILLOW BLIGHT; mycelium variable; conceptacles
scattered or gregarious, minute; appendages simple; sporangia 8-12,
sub-pyriform, containing 4 spores.—On the leaves of Willows, Poplars,
Birch, &c. Not uncommon. (Plate XI. figs. 221-224.)

=Uncinula bicornis=, Lév. MAPLE BLIGHT; amphigenous; mycelium web-like,
effuse, evanescent, or like a membrane and persistent; conceptacles
large, hemispherical, at length depressed; appendages simple, bifid or
dichotomous, uncinate; sporangia 8, sub-pyriform, containing 8
spores.—On the leaves of Maples. Common. (Plate XI. figs. 225-228.)


                          MICROSPHÆRIA, _Lév._

  _Mycelium_ arachnoid; appendages straight, dichotomous; branchlets
        swelling at the tip, or filiform.—_Berk. Outl._, p. 404.

=Microsphæria Hedwigii=, Lév. MEALY GUELDER-ROSE BLIGHT; hypophyllous;
mycelium web-like, evanescent; conceptacles minute, globose, scattered;
appendages few, very little longer than the diameter of the
conceptacles; sporangia 4, ovate, containing 4 spores.—On leaves of
mealy Guelder-rose. Near Greenhithe, Kent.

=Microsphæria penicillata=, Lév. GUELDER-ROSE BLIGHT; amphigenous;
mycelium web-like, effuse, evanescent; conceptacles scattered, minute,
globose; appendages 8-12, equal to the diameter of the conceptacle;
sporangia 4, ovate, rostrate, containing 8 spores.—On leaves of
Guelder-rose and Alder. Probably not uncommon. (Plate XI. fig. 234.)

=Microsphæria Mougeotii=, Lév. TEA-TREE BLIGHT; amphigenous; mycelium
web-like, oftentimes persistent; conceptacles minute, scattered or
gregarious, globose, at length depressed; appendages loosely
dichotomous; sporangia 12-16, on a short pedicel, 2-spored.—On leaves of
_Lycium barbarum_. Near Dartford, Kent. October, 1864.

=Microsphæria Berberidis=, Lév. BERBERRY BLIGHT; amphigenous; mycelium
web-like, oftentimes persistent; conceptacles scattered or gregarious,
globose, minute; appendages few (5-10); branchlets long, divaricate,
obtuse at their apices; sporangia 6, ovate, containing 6-8 spores.—On
leaves of the common Berberry. Autumn. Frequent. (Plate XI. figs.
229-232.)

=Microsphæria grossulariæ=, Lév. GOOSEBERRY BLIGHT; amphigenous;
mycelium web-like, fugacious or persistent; conceptacles scattered or
gregarious, globose, minute; appendages 10-15, vaguely dichotomous,
ultimate branchlets bidentate; sporangia 4-8, ovate, containing 4-5
spores.—On Gooseberry-leaves. Autumn. Frequent.


                           ERYSIPHE, _Hedw._

  Mycelium arachnoid; appendages floccose, simple or irregularly
        branched.—_Berk. Outl._, p. 404.

                        * _Sporangia 2-spored._

=Erysiphe Linkii=, Lév. MUGWORT BLIGHT; amphigenous; mycelium web-like;
fugacious or persistent; conceptacles minute, globose, scattered,
emersed; appendages white, interwoven with the mycelium; sporangia 8-20,
pyriform, with elongated pedicels.—On leaves of Mugwort. Autumn.
Frequent. (Plate XII. figs. 248, 249.)

=Erysiphe lamprocarpa=, Lév. COMPOSITE BLIGHT; amphigenous; mycelium
web-like, fugacious or persistent; conceptacles minute, globose,
scattered, or gregarious; appendages coloured, interwoven with the
mycelium; sporangia 8-16, shortly pedicellate.—On leaves of Salsify,
Scorzonera, Plantain, &c. Autumn. Not uncommon. (Plate XII. figs. 250,
251.)


                       ** _Sporangia 3-8-spored._

=Erysiphe graminis=, D.C. GRASS BLIGHT; amphigenous or epiphyllous;
mycelium effuse, floccose, persistent; conceptacles large, gregarious or
disseminated, hemispherical, at length depressed and semi-immersed;
appendages simple or interwoven with the mycelium; sporangia 20-24,
ovate, pedicellate, with 8 spores.—On leaves of Grasses. Autumn.
Frequent. (Plate XI. figs. 235, 236.)

=Erysiphe Martii=, Lk. PEA BLIGHT; amphigenous; mycelium web-like, very
often evanescent, globose; appendages short, interwoven with the
mycelium; sporangia 4-8, globose, pedicellate, with 4-8 spores.—On
leaves of Peas, Beans, _Umbelliferæ_, and other plants. Autumn. Very
common. (Plate XI. figs. 237-239.)

=Erysiphe Montagnei=, Lév. BURDOCK BLIGHT; amphigenous or hypophyllous;
mycelium web-like, evanescent; conceptacles minute, globose, gregarious
or scattered; appendages distinct from the mycelium; sporangia 8, ovate,
rostrate, with 2-3 spores.—On leaves of Burdock. Not uncommon.

=Erysiphe tortilis=, Lk. CORNEL BLIGHT; hypophyllous; mycelium web-like,
effuse, evanescent; conceptacles minute, globose; appendages ten times
as long, free from the mycelium, flexuose; sporangia 4, ovate, rostrate,
with 4 spores.—On leaves of the common Dogwood. Autumn. Frequent. (Plate
XII. figs. 245, 246.)

=Erysiphe communis=, Schl. BUTTERCUP BLIGHT; hypophyllous; mycelium
effuse, web-like, evanescent or persistent; conceptacles minute,
globose, scattered or gregarious; appendages short; sporangia 4-8,
ovate, rostrate, with 4-8 spores.—On leaves of various _Ranunculaceæ_,
_Leguminosæ_, and other plants. Autumn. Very common. (Plate XI. figs.
240-242.)


                           CHÆTOMIUM, _Kze._

  Perithecium thin, brittle, mouthless; sporangia linear, containing
        dark lemon-shaped spores. _Berk. Outl._, p. 405.

=Chætomium elatum=, Kze. STRAW-BRISTLE MOULD; perithecium sub-ovate,
base radiato-fibrose, hairs of the vertex very long, interwoven,
branched; spores broadly elliptic, apiculate at either end.—On
mouldering straw, reeds, matting, &c. Very common. (Plate XII. figs.
257-259.)

=Chætomium chartarum=, Ehb. PAPER-BRISTLE MOULD; perithecium subglobose,
black, surrounded by a bright yellow spot; spores subglobose.—On paper.
Stibbington, Hants. Rare. (Plate XII. figs. 252, 253.)

=Chætomium glabrum=, B. This species has never been described. It was
recorded, by name only, in Berkeley’s Outlines, and, the specimens being
mislaid, that gentleman is unable to describe it completely and
correctly. “It grew abundantly on straw, and differed from _Chætomium
elatum_ in being perfectly free from hairs.”—(_M. J. B._)—On damp straw.


                          ASCOTRICHA, _Berk._

  Perithecium thin, free, mouthless, seated on loose, branched,
        conidiiferous threads; sporangia linear, containing dark
        elliptic spores.—_Berk. Outl._, p. 405.

=Ascotricha chartarum=, B. PAPER MILDEW; perithecium thin, olive-brown,
seated on radiating flocci; sporangia linear, numerous; spores broadly
elliptic, chocolate-coloured.—On white printed paper in a deal
candle-box. King’s Cliffe. (Plate XII. figs. 254-256.)


                           EUROTIUM, _Link._

  Perithecia reticulated, vesicular, coloured, attached to mucedinous
        threads; sporangia delicate.—_Berk. Outl._, p. 405.

=Eurotium herbariorum=, Lk. HERBARIUM MOULD; perithecium spherical,
sub-depressed, yellow, seated upon radiating expanded, branched,
intricate flocci.—On plants in herbaria, and various decaying
substances. Very common. (Plate XII. figs. 260, 261.)


------------------------------------------------------------------------


                              APPENDIX B.

                                -------


The following species, belonging to those sections of Microscopic Fungi
which are included in this volume, have been found in Britain since the
publication of the preceding Appendix:—

=Peridermium columnare=, Alb. and Schw. Simple, slender, naked,
cylindrical, elongated, lacerated at the apex, white; sporidia
orange.—On _Picea_. Watcombe, near Torquay. September, 1867. (_E.
Parfitt._)

                  *       *       *       *       *

=Æcidium Orchidearum=, Fiedl. ORCHIS CLUSTER-CUP; spots large, pallid,
orbicular or elongated; peridia circinating, semi-immersed; spores
golden-yellow.—On _Orchis latifolia_. Dilham, Norfolk. June, 1866.

                  *       *       *       *       *

=Puccinia discoidearum=, Link. SOUTHERNWOOD BRAND; spots obliterated;
sori subrotund, minute, surrounded by the ruptured epidermis; sporidia
brown, oblong or ovoid, somewhat rhomboidal, with both cells attenuated,
and triangular; peduncles elongated.—On _Artemisia maritima_. Swanscombe
Marshes. 1865.

=Puccinia Virgaureæ=, Lib. GOLDEN-ROD BRAND; spots orbicular, pallid,
then yellowish; sori blackish-brown, minute, punctiform, shining,
clustered, nearly stellate, convex; sporidia oblong, subconstricted,
yellowish-brown above, attenuated and yellowish-white below; peduncles
short.—On leaves of _Solidago virgaurea_. Shere, Surrey. July and
August, 1865. (_Dr. Capron._)

=Puccinia difformis=, Kunze. GOOSEGRASS BRAND; spots yellowish; sori
variable, compact, often in rings; epidermis bullate; sporidia obovate,
obtuse, on short pedicels, brown.—On leaves of _Galium aparine_. July,
1866. Shere and Darenth Usually occurring on or near spots previously
occupied by _Æcidium_.

=Puccinia Apii=, Corda. CELERY BRAND; sori large, confluent, red-brown,
powdery; spores oblong, constricted, brown; epispore smooth, thick;
pedicels short, attenuated.—On leaves of Celery. Autumn, 1866, 1867.

=Puccinia Asari=, Kunze. ASARABACCA BRAND; spots obliterated; sori
small, subglobose, crowded or circinating, ultimately confluent,
surrounded by the ruptured epidermis, usually forming a large, roundish,
convex, pulverulent mass; sporidia brown, elliptic, constricted.—On
leaves of _Asarum Europæum_. Bettws-y-coed, N. Wales. July, 1866.

=Puccinia Mœhringiæ=, Fuckel. It is very doubtful whether this deserves
to rank as a species distinct from _P. Lychnidearum_, Lk. I think not.
The sporidia are rather shorter than in the last-named species, and the
pedicels are very long; otherwise it does not appear to differ from the
typical form.—On _Mœhringia trinervis_. Near Worcester. June, 1867.
(_Dr. Holl._)

=Puccinia fallens=, Cooke. VETCH BRAND; sori few and small, scattered,
intermixed with pustules of _Trichobasis_; sporidia obovate, on rather
long pedicels, of a tawny colour, and slightly constricted at the
septum; epispore smooth.—On leaves of _Vicia sepium_. Liverpool. Autumn,
1865. (_R. McLeod._)

                  *       *       *       *       *

=Uredo Orchidis=, Mart. ORCHIS UREDO; amphigenous; spots reddish-brown;
sori subrotund, arranged in circles, often confluent; sporidia
subglobose, golden-yellow.—On _Listera ovata_ and _Orchis latifolia_.
Crosby, near Liverpool. May, June, 1865. (_R. G. McLeod._)

=Uredo Empetri=, D.C. CROWBERRY UREDO; hypogenous; spots obliterated;
sori oval, scattered: the epidermis at first convex, afterwards ruptured
and concave; sporidia ovoid or subglobose, bright yellow.—On _Empetrum
nigrum_. Near Llanderfel, N. Wales. May, 1865.

=Uredo Euonymi=, Mart. SPINDLE UREDO; spots yellowish; sori roundish,
circinating, often confluent; epidermis erumpent; sporidia ovoid and
slightly coherent, tawny-yellow.—On leaves of _Euonymus Europæus_.
Darenth Wood, Kent. August, 1864. Rare.

=Uredo Tropæoli=, Desmz. NASTURTIUM UREDO: hypogenous; spots
pale-yellow; sori minute, roundish, scattered or confluent; sporidia
ovoid or subglobose, orange.—On leaves of _Tropæolum aduncum_. Shere.
October, 1865. (_Dr. Capron._)

                  *       *       *       *       *

=Trichobasis fallens=, Cooke. CLOVER RUST; spots obliterated; sori
amphigenous, numerous, scattered, subrotund, brown, surrounded by the
remains of the ruptured epidermis; spores sub-ovate; pedicels short,
hyaline, evanescent; epispore verrucose. _Uredo fallens_, Desmz.—On
leaves of Clover, &c. September. Not uncommon.

                  *       *       *       *       *

=Uromyces graminum=, Cooke. COCKSFOOT RUST; epiphyllous; sori oblong or
confluent and linear, convex, black and shining, so as easily to be
confounded on casual observation with _Dothidea graminis_, at length
bursting longitudinally; sporidia subglobose or ovate, tawny, with
hyaline pedicels of variable length.—On leaves of _Dactylis glomerata_.
Shere. October, 1865. (_Dr. Capron._)

=Uromyces concentrica=, Lév. Described at p. 208 as _Trichobasis
Scillarum_, B.; but it appears to be a good _Uromyces_, and has been
placed in that genus by Lévielle.

=Uromyces sparsa=, Lév. SANDWORT RUST; spots pallid; sori subrotund and
oval, amphigenous and cauline; epidermis erumpent; sporidia ovoid,
brownish; peduncles thickened, short.—On _Spergularia rubra_. Swanscombe
Marshes. June, 1865.

=Uromyces Polygoni=, Fuckel. KNOTGRASS RUST; cauline; sori elongated and
confluent, convex, surrounded by the remains of the ruptured epidermis;
sporidia subglobose or globose, smooth, yellowish-brown; pedicels very
long, thickened, hyaline, persistent. _Capitularia Polygoni_, Rabh.—On
the stems of _Polygonum aviculare_. October. Common.

                  *       *       *       *       *

=Cystopus spinulosus=, De Bary. THISTLE (WHITE) RUST; conidia in time
much elongated; sori erumpent on both surfaces of the leaves, white;
oospores globose; epispore brown; tubercles minute, solid, very
prominent, often acute and spinulose.—On Thistles. Bungay, Suffolk.
September, 1865.

                  *       *       *       *       *

=Peronospora candida=, Fuckel. PRIMROSE MOULD; densely cæspitose, white;
threads erect, dichotomously branched; ultimate branchlets short,
spreading; sporidia ovate.—On leaves of Primrose. Near Corwen, N. Wales.
July, 1866.


    The following genus is entirely new to Britain. Its position is
                  next to _Microsphæria_ at page 219.


                          PODOSPHÆRA, _Kunze_.

Mycelium effuse, web-like, evanescent; conceptacles sphærical,
containing one subglobose 8-spored sporangium; spores ovate; appendages
few, dichotomous, thickened at their extremities, hyaline.

=Podosphæra Kunzei=, Lév. PLUM BLIGHT; amphigenous; conceptacles minute,
scattered, globose; appendages three times the length of the diameter of
the conceptacles.—On leaves of _Prunus domestica_. Shere, Surrey. Sept.,
1865. (_Dr. Capron._)

=Podosphæra clandestina=, Lév. HAWTHORN BLIGHT; amphigenous;
conceptacles minute, globose, scattered; appendages (8-10) equal in
length to the diameter of the conceptacles; branches short and rounded
at their extremities.—On leaves of the Hawthorn. Upper Holloway.
October, 1864; Shere, Surrey, September, 1865. (_E. C._)

                  *       *       *       *       *

=Uncinula Wallrothii=, Lév. SLOE BLIGHT; amphigenous; mycelium web-like,
evanescent; conceptacles minute, scattered; sporanges 12-16,
pear-shaped, 6-spored; appendages numerous, twice the length of the
diameter of the conceptacles.—On leaves of the Sloe, _Prunus spinosa_.
Shere, Surrey. October, 1865. (_Dr. Capron._)

                  *       *       *       *       *

=Microsphæria comata=, Lév. SPINDLE BLIGHT; hypophyllous; mycelium
web-like, fugacious; conceptacles scattered, minute, globose; sporanges
8, ovate, with a beak-like termination at their base, 4-spored;
appendages few, six times the length of the diameter of the
conceptacles.—On _Euonymus Europæus_. Shere, Surrey. August, 1865. (_Dr.
Capron._)

                  *       *       *       *       *

=Erysiphe horridula,= Lév. BORAGE BLIGHT; amphigenous; mycelium
web-like, sometimes persistent; conceptacles minute, globose, scattered
or clustered; sporanges 20-24, oblong-ovate, attenuated downwards,
containing 3-4 spores; appendages short, flexuose, and bent upwards.—On
leaves of _Lycopsis arvensis_. Shere. October, 1865. (_Dr. Capron._)

                  *       *       *       *       *

=Chætomium murorum=, Corda. WALL BRISTLE-MOULD; gregarious, glaucous,
then blackish; perithecium globose, brown; hairs circinate, erect,
septate, pulverulent; spores oblong, yellowish. On plaster. Rare. (_M.
J. B._)


------------------------------------------------------------------------



                                ADDENDA.

                                -------

[The following species have been added to the British Flora since the
    publication of the Appendix.]

=Æcidium Parnassiæ=, Grav. PARNASSIA CLUSTER-CUPS; hypophyllous; spots
pallid; peridia in subrotund patches, irregularly disposed,
tawny-yellow, between urceolate and concave; the margin thick and nearly
entire; spores pallid. _Duby. Bot. Gall._ ii. p. 904.—On leaves of
_Parnassia palustris_, near Glasgow. (_Dr. Greville._) The original
specimen is in the Edinburgh Herbarium.

=Æcidium Statices=, Desm. SEA-LAVENDER CLUSTER-CUPS; hypophyllous; spots
subrotund, or confluent and irregular, purple; peridia in subrotund
circinating clusters, sometimes irregularly disposed on the nerves and
petioles; urceolate; margin lacerated, white; spores orange. _Desm.
Exs._ No. 132. _Cooke, Exs._ No. 444.—On leaves and petioles of
_Statices_. June, July. Fleetwood, 1859 (_Rev. A. Bloxam_). Walney
Island, Lancashire, 1871 (_C. Bailey_). Near Basingstoke, 1871 (_R. S.
Hill_). Near Chichester, 1872 (_F. V. Paxton_).

=Chætomium funicolum=, Cooke. TWINE BRISTLE-MOULD; perithecia scattered,
sub-ovate, black; hairs of the vertex very long, dichotomous or simple,
erect, slender, acute, black; sporidia lemon-shaped, dingy brown.—On
twine suspended in a vessel containing water at the British Museum. (_W.
Carruthers, F.R.S._) March, 1872. This species is most closely allied to
_C. elatum_, but much smaller and neater. It is wholly black, and
without the fibrous base of _C. elatum_. The hairs are more delicate,
not having half the diameter, and the sporidia are scarcely more than
half as long or broad. A species of _Polyactis_ afterwards made its
appearance on the same mycelium on some portion of the twine left behind
with a few immature perithecia.


------------------------------------------------------------------------



                         EXPLANATION OF PLATES.

                                -------


     Plate fig.

      I.    1.   Goatsbeard with its cluster-cups (_Æcidium
                   Tragopogonis_).

       〃    2.   Fragment of same, slightly magnified.

       〃    3.   Section of cluster-cup, further magnified.

       〃    4.   Leaf of wood-anemone with its cluster-cups
                   (_Æcidium leucospermum_).

       〃    5.   Portion of same, slightly magnified.

       〃    6.   Anemone cluster-cups, further magnified.

       〃    7.   Leaf of Berberry with cluster-cups (_Æcidium
                   Berberidis_).

       〃    8.   Cluster of cups from the Berberry, as seen with a
                   lens.

       〃    9.   Cluster-cups of Berberry, magnified.

       〃    10.  Nettle-stem distorted by growth of cluster-cups
                   (_Æcidium Urticæ_).

       〃    11.  Nettle cluster-cups, magnified.

      II.   12.  Leaf of Pilewort with groups of cluster-cups
                   (_Æcidium Ranunculacearum_).

       〃    13.  Group of cluster-cups from Pilewort, as seen with
                   a lens.

       〃    14.  Section of Pilewort cluster-cups, magnified.

       〃    15.  Bedstraw cluster-cups (_Æcidium Galii_) on the
                   Great Hedge Bedstraw.

       〃    16.  Tip of leaflet with cluster of cups, viewed
                   through a lens.

       〃    17.  Bedstraw cluster-cup from same, magnified.

       〃    18.  Leaflets of Mountain-ash with horn-shaped
                   cluster-cups (_Rœstelia cornuta_).

       〃    19.  Group of Mountain-ash cluster-cups, magnified.

       〃    20.  Pear-leaf with its cluster-cups (_Rœstelia
                   cancellata_).

       〃    21.  Cluster-cup from the same, magnified.

       〃    22.  Leaves and fruit of Hawthorn with lacerated
                   cluster-cups (_Rœstelia lacerata_).

       〃    23.  Elongated cells forming the walls of the
                   cluster-cups, × 250.

       〃    24.  Single cell, more highly magnified, with its
                   parallel striæ.

       〃    25.  Cluster-cups from fruit of Hawthorn, magnified.

       〃    26.  Section of same, further magnified.

       〃    27.  Fir-leaves bearing cluster-cups (_Peridermium
                   Pini_).

       〃    28.  Isolated cup of same, magnified.

     III.   29.  Many-jointed fruit of Burnet chain-brand
                   (_Xenodochus carbonarius_), magnified.

       〃    30.  Leaflets of Burnet with rust on the lower, and
                   brand (_Aregma acuminatum_) on the upper
                   leaflets.

       〃    31.  Spores of Burnet rust (_Lecythea Poterii_) × 230.

       〃    32.  Fruit of Burnet brand (_Aregma acuminatum_).

       〃    33.  Leaf of Barren Strawberry with rust and brand
                   intermixed.

       〃    34.  Spores of Barren Strawberry rust × 230.

       〃    35.  Fruit of Strawberry brand (_Aregma obtusatum_) ×
                   300.

       〃    36.  Leaflet of Rose with its rust and brand
                   intermixed.

       〃    37.  Spores of Rose rust (_Lecythea Rosæ_) × 230.

       〃    38.  Fruit of Rose brand (_Aregma mucronatum_) × 300.

       〃    39.  Leaflet of Bramble, with its rust and brand
                   intermixed.

       〃    40.  Spores of Bramble rust (_Lecythea Ruborum_) × 230.

       〃    41.  Fruit of Bramble brand (_Aregma bulbosum_) × 300.

       〃    42.  Leaflet of Raspberry with its brand.

       〃    43.  Fruit of Raspberry brand (_Aregma gracile_) × 230.

       〃    44.  Cluster of fruits of Rose brand (_Aregma
                   mucronatum_) × 230.

       〃    45.  Fruit of Bramble brand (_Aregma bulbosum_) in
                   active germination, with sporidia at the tips of
                   the threads × 300.

       〃    46.  Fruit of Bramble brand (_Aregma bulbosum_)
                   ruptured, with inner cell escaping × 250 (_F.
                   Currey_).

       〃    47.  Portion of leaflet of Meadow-sweet with its brand.

       〃    48.  Spores of Meadow-sweet brand (_Triphragmium
                   ulmariæ_) × 300.

       〃    49.  Spore of Meadow-sweet brand (_Triphragmium
                   ulmariæ_) in germination, with sporidia borne on
                   the germ-tubes × 300 (_Tulasne_).

       〃    50.  Sprig of _Thesium humifusum_ bearing
                   Bastard-toadflax cluster-cups (_Æcidium
                   Thesii_).

       〃    51.  Portion of leaf of same, with cluster-cups,
                   enlarged.

       〃    52.  Leaflet of _Trientalis Europæa_ with its smut
                   (_Tuburcinia Trientalis_).

       〃    53.  Spores of the same × 320.

       〃    54.  Spores of Potato smut (_Tuburcinia scabies_) ×
                   320. (_Berkeley._)

       〃    55.  Leaflet of Alexanders (_Smyrnium olusatrum_) with
                   its brand.

       〃    56.  Spores of Alexanders brand (_Puccinia Smyrnii_) ×
                   320.

      IV.   57.  Wheat-straw attacked by mildew (_Puccinia
                   graminis_).

       〃    58.  Cluster of spores of corn-mildew, magnified
                   (_Bauer_).

       〃    59.  Single spore of corn-mildew (_Puccinia graminis_)
                   × 300.

       〃    60.  Portion of blade of grass with coronated mildew
                   (_Puccinia coronata_).

       〃    61.  Portion of same enlarged, showing the pustules, or
                   sori.

       〃    62.  Spore of coronated mildew (_Puccinia coronata_) ×
                   highly.

       〃    63.  Portion of leaf of Spear-thistle with its brand
                   (_Puccinia syngenesiarum_).

       〃    64.  Spores of Thistle brand (_Puccinia syngenesiarum_)
                   × 320.

       〃    65.  Leaf of Wood-anemone with brand (_Puccinia
                   anemones_).

       〃    66.  Spore of Anemone brand (_Puccinia anemones_) ×
                   320.

       〃    67.  Leaf of _Centaurea nigra_ with brand.

       〃    68.  Spores of Composite-brand (_Puccinia
                   compositarum_) × 320.

       〃    69.  Leaf of Mint with Mint brand (_Puccinia menthæ_).

       〃    70.  Spore of Mint brand (_Puccinia menthæ_) × 350.

       〃    71.  Portion of leaf of Earth-nut with brand (_Puccinia
                   umbelliferarum_).

       〃    72.  Spore of Earth-nut brand (_Puccinia
                   umbelliferarum_) × 320.

       〃    73.  Leaf of Ground-ivy with its brand (_Puccinia
                   Glechomatis_).

       〃    74.  Spore of Ground-ivy brand (_Puccinia Glechomatis_)
                   × 320.

       〃    75.  Pustule of brand surrounded by the ruptured
                   epidermis, magnified.

       〃    76.  Portion of leaf and stem of Goatsbeard with brand.

       〃    77.  Spores of the same × 320.

       〃    78.  Portion of leaf of Willow-herb with its brand
                   (_Puccinia pulverulenta_).

       〃    79.  Spores of Willow-herb brand (_Puccinia
                   pulverulenta_) × 320.

       〃    80.  Leaf of Pennywort with brand (_Puccinia
                   umbilici_).

       〃    81.  Spores of Pennywort-brand (_Puccinia umbilici_) ×
                   320.

       〃    82.  Portion of leaf of Dandelion with its brand.

       〃    83.  Spores of Variable-brand (_Puccinia variabilis_) ×
                   320.

      V.    84.  Grain of  Wheat infected with Fœtid smut
                   (_Tilletia caries_).

       〃    85.  Longitudinal section of the same.

       〃    86.  Spores of Fœtid smut (_Tilletia caries_) mixed
                   with delicate branching threads × 320.

       〃    87.  Spores of Fœtid smut in germination × highly.

       〃    88.  Sporidia of the first order borne on the
                   germinating tubes of the fœtid smut (_Tilletia
                   caries_) × highly.

       〃    89.  Sporidia of the first order, showing their
                   transverse connection, × highly.

       〃    90.  Sporidia of the first order, producing sporidia of
                   the second order, × highly.

       〃    91.  Sporidium of the second order in active
                   germination.

       〃    92.  Deformed flower-head of Goatsbeard infested with
                   smut (_Ustilago receptaculorum_).

       〃    93.  Floret removed, sprinkled with spores of the smut,
                   enlarged.

       〃    94.  Spores of Goatsbeard smut (_Ustilago
                   receptaculorum_) × 460.

       〃    95.  The same in active germination × 460 (_Tulasne_).

       〃    96.  Beaksedge (_Rhyncospora alba_) with its smut
                   (_Ustilago Montagnei_).

       〃    97.  Spores of _Ustilago Montagnei_ × 460.

       〃    98.  Ear of Barley infected with smut (_Ustilago
                   segetum_).

       〃    99.  Spores of Corn-smut (_Ustilago segetum_) × 460.

       〃   100.  Grass with its smut (_Ustilago hypodytes_).

       〃   101.  Spores of Grass-smut (_Ustilago hypodytes_).

       〃   102.  Flowers of Bladder-campion with anther smut
                   (_Ustilago antherarum_).

       〃   103.  Anther distorted by smut (_Ustilago antherarum_).

       〃   104.  Spores of Anther smut (_Ustilago antherarum_) ×
                   460.

       〃   105.  Portion of leaf of water grass with Elongated smut
                   (_Ustilago longissima_).

       〃   106.  Pustule of same, enlarged.

       〃   107.  Spores of Elongated smut (_Ustilago longissima_) ×
                   very highly.

       〃   108.  Spores of Maize smut (_Ustilago maydis_) × 460.

      VI.  109.  Sedge (_Carex recurva_) with Sedge smut (_Ustilago
                   urceolorum_).

       〃   110.  Single fruit covered with the smut.

       〃   111.  Spores of Sedge smut (_Ustilago urceolorum_) ×
                   460.

       〃   112.  Flower of _Polygonum persicaria_ distorted by
                   Utricle smut (_Ustilago utriculosa_).

       〃   113.  Section of the same (_Tulasne_).

       〃   114.  Inflorescence of _Polygonum hydropiper_ with
                   Utricle smut (_Ustilago utriculosa_).

       〃   115.  Section of infected flower of _Polygonum
                   hydropiper_.

       〃   116.  Spores of Utricle smut (_Ustilago utriculosa_) ×
                   460.

       〃   117.  Leaf of Cocksfoot, grass with smut (_Ustilago
                   Salveii_).

       〃   118.  Portion of leaf, showing pustules, × slightly.

       〃   119.  Spores of Cocksfoot smut (_Ustilago Salveii_) ×
                   320.

       〃   120.  Grass stem with Banded smut (_Ustilago grammica_).

       〃   121.  Portion of same, showing arrangement of the
                   pustules, × slightly.

       〃   122.  Spores of banded smut (_Ustilago grammica_) × 320.

       〃   123.  Inflorescence of Scabious with Floret smut
                   (_Ustilago flosculorum_).

       〃   124.  Floret occupied by the smut.

       〃   125.  Spores of Floret smut (_Ustilago flosculorum_) ×
                   320.

       〃   126.  Sedge (_Carex riparia_) attacked by Olive smut
                   (_Ustilago olivacea_).

       〃   127.  Spores of Olive smut (_Ustilago olivacea_) × 460.

       〃   128.  Reed stem with smut (_Ustilago typhoides_).

       〃   129.  Spores of Reed smut (_Ustilago typhoides_) × 320.

       〃   130.  Leaf of Periwinkle with its rust (_Trichobasis
                   vincæ_).

       〃   131.  Spores of Periwinkle rust (_Trichobasis vincæ_) ×
                   320.

       〃   132.  Spores of Periwinkle brand (_Puccinia vincæ_) ×
                   320.

     VII.  133.  Leaf of Mercury with its rust (_Uredo confluens_).

       〃   134.  Spores of Mercury rust (_Uredo confluens_) × 320.

       〃   135.  Leaf of Enchanter’s Nightshade with its rust.

       〃   136.  Spores of Nightshade rust (_Uredo Circææ_) × 320.

       〃   137.  Leaf of Sorrel with Twin-faced rust (_Uredo
                   bifrons_).

       〃   138.  Pustule of Twin-faced rust seated on a coloured
                   spot × slightly.

       〃   139.  Spores of the same rust × 320.

       〃   140.  Leaf of Wheat with Corn rust (_Trichobasis
                   rubigo-vera_).

       〃   141.  Pustules of the same rust × slightly.

       〃   142.  Spores of Round corn rust × 320.

       〃   143.  Tuft of spores of Elongated corn rust
                   (_Trichobasis linearis_) magnified.

       〃   144.  Spores of Elongated corn rust (_Trichobasis
                   linearis_) × 320.

       〃   145.  Leaf of Groundsel with its rust (_Trichobasis
                   Senecionis_).

       〃   146.  Spores of Groundsel rust (_Trichobasis
                   Senecionis_) × 320.

       〃   147.  Wild Rose with Golden rust (_Uromyces Ulmariæ_).

       〃   148.  Spores of Golden rust × 320.

       〃   149.  Leaf of Vetch with Long-stemmed rust (_Uromyces
                   appendiculata_).

       〃   150.  Spores of the same × 460.

       〃   151.  Leaf of Common thistle with Sweet-smelling rust
                   (_Trichobasis suaveolens_).

       〃   152.  Spores of Sweet rust (_Trichobasis suaveolens_) ×
                   320.

       〃   153.  Spermogone of Sweet rust, from common thistle, ×
                   highly (_De Bary_).

       〃   154.  Clover leaf with Short-stemmed rust (_Uromyces
                   apiculosa_).

       〃   155.  Spores of Short-stemmed rust × 320.

       〃   156.  Leaf of Pilewort with its rust (_Uromyces
                   Ficariæ_).

       〃   157.  Spores of Pilewort rust (_Uromyces Ficariæ_) ×
                   320.

       〃   158.  Portion of leaf of _Luzula_ with Oblong rust
                   (_Trichobasis oblongata_).

       〃   159.  Spores of Oblong rust (_Trichobasis oblongata_) ×
                   320.

     VIII. 160.  Leaf of Sallow with its rust (_Lecythea
                   capræarum_).

       〃   161.  Spores of Sallow rust (_Lecythea capræarum_) ×
                   320.

       〃   162.  Bramble leaf with Ringed rust (_Lecythea gyrosa_).

       〃   163.  Pustule of Ringed rust (_Lecythea gyrosa_) ×
                   slightly.

       〃   164.  Spores of Ringed rust (_Lecythea gyrosa_) × 320.

       〃   165.  Purging Flax with its rust (_Lecythea Lini_).

       〃   166.  Pustule of the same × slightly.

       〃   167.  Spores of Flax rust (_Lecythea Lini_) × 320.

       〃   168.  Leaf of Flukewort with its rust (_Trichobasis
                   hydrocotyles_).

       〃   169.  Spores of _Trichobasis hydrocotyles_ × 320.

       〃   170.  Portion of leaf of Sedge with its rust
                   (_Trichobasis caricina_).

       〃   171.  Spores of Sedge rust (_Trichobasis caricina_) ×
                   320.

       〃   172.  Whorl of leaves of Hedge Bedstraw with Bedstraw
                   brand (_Puccinia Galii_).

       〃   173.  Spores of Bedstraw brand (_Puccinia Galii_) × 320.

       〃   174.  Leaf of Tutsan with St. John’s-wort rust (_Uredo
                   hypericorum_).

       〃   175.  Spores of St John’s-wort rust (_Uredo
                   hypericorum_) × 320.

       〃   176.  Leaves of Cow-wheat with its rust (_Coleosporium
                   rhinanthacearum_).

       〃   177.  Spores of Cow-wheat rust (_Coleosporium
                   rhinanthacearum_) × 320.

       〃   178.  Portion of leaf of Sow-thistle with its rust
                   (_Coleosporium sonchi-arvensis_).

       〃   179.  Spores of Sow-thistle rust × highly (_De Bary_).

       〃   180.  Portion of Coltsfoot leaf with its rust
                   (_Coleosporium Tussilaginis_).

       〃   181.  Spores of Coltsfoot rust × highly.

       〃   182.  Group of spores of Coltsfoot rust _in situ_ ×
                   highly (_Tulasne_).

      IX.  183.  Leaf of Buttercup with Buttercup smut (_Polycystis
                   pompholygodes_).

       〃   184.  Fruit of Buttercup smut (_Polycystis
                   pompholygodes_) × 460.

       〃   185.  Violet leaf distorted by Violet smut (_Polycystis
                   Violæ_).

       〃   186.  Fruit of Violet smut (_Polycystis Violæ_) × 460.

       〃   187.  Portion of Rye-leaf with Rye smut (_Polycystis
                   parallela_).

       〃   188.  Fruit of Rye smut (_Polycystis parallela_) ×460.

       〃   189.  Dead Birch leaf with Birch wedge-rust (_Melampsora
                   betulina_).

       〃   190.  Winter spores of (_Melampsora betulina_) × 460.

       〃   191.  Portion of Sallow leaf with Willow wedge-rust
                   (_Melampsora salicina_).

       〃   192.  Winter spores of _Melampsora salicina_ × 460.

       〃   193.  Leaves of Spurge with Spurge wedge-rust
                   (_Melampsora Euphorbiæ_).

       〃   194.  Winter spores of _Melampsora Euphorbiæ_ × highly.

       〃   195.  Portion of Poplar-leaf with Poplar wedge-rust
                   (_Melampsora populina_).

       〃   196.  Winter spores of _Melampsora populina_ × 460.

       〃   197.  Winter spores of _Melampsora betulina_ in active
                   germination—_a_ sporidia × 466 (_Tulasne_).

      X.   198.  Fruit of Shepherd’s-Purse with White rust
                   (_Cystopus candidus_).

       〃   199.  Portion of Cabbage-leaf with White rust (_Cystopus
                   candidus_).

       〃   200.  Conidia of White rust (_Cystopus candidus_) × 360.

       〃   201.  Portion of Goatsbeard-leaf with White rust
                   (_Cystopus cubicus_).

       〃   202.  Conidia of Goatsbeard white rust (_Cystopus
                   cubicus_) × 360.

       〃   203.  Portion of Mycelium producing the first of a chain
                   of conidia × 400.

       〃   204.  Mycelium of White rust with sucker-like processes
                   × 360.

       〃   205.  Mycelium of White rust with nascent oogonia × 360.

       〃   206.  Oogonium of Crucifer white rust (_Cystopus
                   candidus_) × 400 (_De Bary_).

       〃   207.  The same, further advanced, ruptured, with
                   zoospores, × 400.

       〃   208.  Free zoospores of White rust, with their ciliæ, ×
                   400 (_De Bary_).

       〃   209.  Resting zoospores in germination × 400 (_De
                   Bary_).

       〃   210.  Oogonium of Goatsbeard white rust (_Cystopus
                   cubicus_) × 400 (_De Bary_).

       〃   211.  Oogonium of Sandwort mould (_Peronospora
                   arenariæ_) × 400 (_De Bary_).

       〃   212.  Oogonium of Pea mould (_Peronospora viciæ_) × 400
                   (_De Bary_).

       〃   213.  Oogonium of Veronica mould (_Peronospora grisea_)
                   × 400 (_De Bary_).

       〃   214.  Oogonium of Spinach mould (_Peronospora effusa_) ×
                   400 (_De Bary_).

       〃   215.  Leaf of Goosefoot with mould (_Peronospora
                   effusa_).

      XI.  216.  Conceptacle of Hop mildew (_Sphærotheca
                   castagnei_) × 80.

       〃   217.  Conceptacle of Rose blight (_Sphærotheca pannosa_)
                   × 80.

       〃   218.  Sporangium of _Sphærotheca pannosa_ × highly.

       〃   219.  Conceptacle of Hazel blight (_Phyllactinia
                   guttata_) × 80.

       〃   220.  Sporangium of _Phyllactinia guttata_ × highly.

       〃   221.  Portion of leaf of Willow with Willow blight
                   (_Uncinula adunca_).

       〃   222.  Conceptacle of Willow blight (_Uncinula adunca_) ×
                   80.

       〃   223.  Tip of one of the appendages × highly.

       〃   224.  Sporangium of Willow blight (_Uncinula adunca_) ×
                   highly.

       〃   225.  Conceptacle of Maple blight (_Uncinula bicornis_)
                   × 80.

       〃   226.  Tip of one of the appendages of _Uncinula
                   bicornis_ × highly.

       〃   227.  Furcate tip of one of the appendages of the Maple
                   blight (_Uncinula bicornis_) × highly.

       〃   228.  Sporangium of _Uncinula bicornis_ × highly.

       〃   229.  Leaf of Berberry with Berberry blight
                   (_Microsphæria Berberidis_).

       〃   230.  Conceptacle of Berberry blight × 80.

       〃   231.  Tip of one of the appendages of Berberry blight
                   (_Microsphæria Berberidis_) × highly.

       〃   232.  Sporangium of Berberry blight × highly.

       〃   233.  Tip of appendage of a continental species of
                   blight (_Microsphæria Ehrenbergii_) × highly
                   (_Léveillé_).

       〃   234.  Tip of appendage of Alder blight (_Microsphæria
                   penicillata_) × highly.

       〃   235.  Portion of Grass leaf with blight (_Oidium
                   monilioides_).

       〃   236.  Tuft of conidia of _Oidium monilioides_ × 120.

       〃   237.  Leaflet of Garden Pea with Pea blight (_Erysiphe
                   Martii_).

       〃   238.  Conceptacle of Pea blight (_Erysiphe Martii_) ×
                   80.

       〃   239.  Sporangium of _Erysiphe Martii_ × highly.

       〃   240.  Conceptacle of Buttercup blight (_Erysiphe
                   communis_) × 80.

       〃   241.  Sporangium of _Erysiphe communis_ × highly.

       〃   242.  Sucker from the mycelium of _Erysiphe communis_,
                   magnified.

     XII.  243.  Conceptacle of Mealy Guelder-rose blight
                   (_Microsphæria Hedwigii_) × 80.

       〃   244.  Sporangium of same, containing spores, × highly.

       〃   245.  Conceptacle of Cornel blight (_Erysiphe tortilis_)
                   × 80.

       〃   246.  Sporangium of same, containing spores, × highly.

       〃   247.  Tip of appendage of _Microsphæria Hedwigii_ ×
                   highly.

       〃   248.  Sporangium of Mugwort blight (_Erysiphe Linkii_),
                   containing spores, × highly.

       〃   249.  Conceptacle of Mugwort blight (_Erysiphe Linkii_)
                   × 80.

       〃   250.  Sporangium and spores of Plantain blight
                   (_Erysiphe lamprocarpa_) × highly.

       〃   251.  Conceptacle of Plantain blight (_Erysiphe
                   lamprocarpa_) × 80.

       〃   252.  Conceptacle of Paper bristle-mould (_Chætomium
                   chartarum_) magnified.

       〃   253.  Sporidium of the same, further magnified.

       〃   254.  Conceptacle of Paper mildew (_Ascotricha
                   chartarum_) magnified (_Berkeley_).

       〃   255.  Portion of thread of same with conidia, further
                   magnified (_Berkeley_).

       〃   256.  Sporangium of same, containing spores
                   (_Berkeley_).

       〃   257.  Piece of straw with Bristle mould (_Chætomium
                   elatum_).

       〃   258.  Conceptacle of same, slightly magnified.

       〃   259.  Section of same, further magnified.

       〃   260.  Dead leaf over-run with Herbarium mildew
                   (_Eurotium herbariorum_).

       〃   261.  Conceptacles of the same, seated on their
                   mycelium, magnified.

     XIII. 262.  Fertile thread of Turnip mould (_Peronospora
                   parasitica_).

       〃   263.  Fertile thread of Onion mould (_Peronospora
                   Schleideniana_).

     XIV.  264.  Fertile thread of Potato mould (_Peronospora
                   infestans_).

       〃   265.  Fertile thread of Lettuce mould (_Peronospora
                   gangliformis_).

      XV.  266.  Fertile thread of Pea mould (_Peronospora Viciæ_).

       〃   267.  Fertile thread of Anemone mould (_Peronospora
                   curta_).

     XVI.  268.  Fertile thread of Sandwort mould (_Peronospora
                   arenariæ_).

       〃   269.  Fertile thread of Dock mould (_Peronospora
                   obliqua_) × 320.


------------------------------------------------------------------------



                                 INDEX.


                    PAGE

 Acrospores, 141
 Æcidiacei, 189
 _Æcidiolum exanthematum_, 22
 _Æcidium_, 5
 —— (Descriptions), 190
 —— _Euphorbiæ_, 11
 —— _Galii_, 15
 —— _leucospermum_, 11
 —— _quadrifidum_, 11
 —— _Ranunculacearum_, 12
 —— _Saniculæ_, 15
 —— _Thesii_, 15
 —— _Tragopogonis_, 5
 Alternation of Generations, 38
 Anemone brand, 60
 —— cluster-cups, 10
 Anther smut, 85
 Antheridia, 129
 Appendages or fulcra, 165
 APPENDIX, 189
 _Aregma bulbosum_, 69
 —— (Descriptions), 195
 —— _gracilis_, 71
 —— _mucronatum_, 34
 —— _obtusatum_, 73
 _Artotrogus_, 151
 Asci, 35
 _Ascomyces Rumicis_, 161
 _Ascotricha chartarum_, 175
 —— (Descriptions), 221

 Bean rust, 104
 Bedstraw cluster-cups, 15
 Beet rust, 104
 Berberry cluster-cups, 16
 Berberry mildew, 170
 Birch rust, 118
 —— wedge-rust, 118
 Blackberry brand, 68
 Bladder brand, 86
 Blight, Berberry, 170
 —— Burdock, 174
 —— Crowfoot, 173
 —— Dogwood, 174
 —— Gooseberry, 171
 —— Guelder-rose, 171
 —— Hazel, 168
 —— Hop, 169
 —— Indian Cotton, 177
 —— Maple, 167
 —— Mealy Guelder-rose, 172
 —— Mugwort, 174
 —— Pea, 173
 —— Plantain, 174
 —— Rose, 166
 —— Salsify, 174
 —— Willow, 169
 _Boletus cyanescens_, 106
 _Botrytis devastatrix_, 153
 —— _fallax_, 153
 —— _infestans_, 153
 Bramble brand, 68
 Brand, Anemone, 60
 —— Bladder, 86
 —— Bramble, 68
 —— Burnet chain, 73
 —— Centaury, 63
 —— Complex, 67
 —— Dust, 76
 —— Earth-nut, 64
 —— Goatsbeard, 65
 —— Ground-ivy, 59
 —— Meadow-sweet, 67
 —— Mint, 58
 —— Pepper, 86
 —— Periwinkle, 103
 —— Raspberry, 71
 —— Sanicle, 64
 —— Strawberry, 72
 —— Thistle, 62
 Bristle-moulds, 175
 Buckthorn cluster-cups, 16
 Bunt, 86
 Bunt, germination, 87
 Burdock blight, 174
 Burnet chain-brand, 73
 Butter-bur rust, 122
 Buttercup blight, 173
 —— cluster-cups, 12

 Cabbage rust, 136
 Campanula rust, 123
 Centaury brand, 63
 _Chætomium_ (Descriptions), 221
 —— _elatum_, 175
 Classification, 189
 Clover rust, 116
 CLUSTER-CUPS, 2
 Cluster-cup, Anemone, 10
 —— Bedstraw, 15
 —— Berberry, 16
 —— Buckthorn, 16
 —— Buttercup, 12
 —— Fir-tree, 20
 —— Goatsbeard, 3
 —— Hawthorn, 17
 —— Houseleek, 21
 —— Mountain-Ash, 19
 —— Nettle, 14
 —— Pear-tree, 18
 —— Sanicle, 14
 —— Spurge, 11
 —— Violet, 13
 Cocksfoot smut, 83
 _Coleosporium_, 119
 —— _Campanulæ_, 122
 —— (Descriptions), 212
 —— _petasites_, 122
 —— _tussilaginis_, 120
 _Coleosporium sonchi-arvensis_, 122
 —— _Rhinanthacearum_, 122
 Collecting fungi, 179
 Coltsfoot rust, 120
 COMPLEX BRANDS, 67
 Complex smuts, 90
 Composite rust, 105
 Conceptacles, 165
 Conidia, 126
 _Coniomycetes_, 5
 Conjurer of Chalgrave’s fern, 61
 Corn mildew, 48
 —— mildew, germination, 55
 —— rust, 49, 52, 95
 —— smut, 79
 Cornel blight, 174
 Coronated mildew, 56
 Cotton blight in India, 177
 Cow-parsnip rust, 105
 Cow-wheat rust, 122
 Crowfoot blight, 173
 Crucifer white rust, 136
 _Cryptosporium Neesii_, 35
 _Cystopus_, 124, 136
 —— _candidus_, 136
 —— _cubicus_, 136
 —— (Descriptions), 214
 —— _Lepigoni_, 136

 Dandelion parasites, 61
 De Bary’s experiments, 129
 Descriptions, 189
 DI-MORPHISM, 33
 Diseases of wheat, 85
 Dock mould, 160
 Dogwood blight, 174
 _Dothidea ribis_, 36
 Dust-brand, 76

 Earth-nut brand, 64
 Elongated corn rust, 95
 —— smut, 84
 Enchanter’s Nightshade rust, 112
 _Endophyllum_, 20
 —— (Descriptions), 194
 Endospore, 40
 Epispore, 40
 _Erineum acerinum_, 170
 _Erysiphe communis_, 173
 —— (Descriptions), 220
 —— _lamprocarpa_, 174
 —— _Linkii_, 174
 —— _Martii_, 173
 —— _Montagnei_, 174
 —— _tortilis_, 174
 _Eurotium_ (Descriptions), 222
 —— _herbariorum_, 177
 Examining fungi, 183

 Fern rust, 112
 Fungi, species of, 45

 Generations, alternation of, 38
 Genus and species, 58
 Germination of mildew, 55
 —— of pea rust, 40
 Goatsbeard cluster-cups, 3
 —— smut, 82
 —— white rust, 136
 Goat-willow rust, 116
 Golden-rose rust, 113
 Gonosphere, 130
 Gooseberry blight, 171
 Ground-ivy brand, 59
 Groundsel rust, 97
 Guelder-rose blight, 171
 _Gymnosporangium_ (Descriptions), 201

 Hawthorn cluster-cups, 17
 Hazel blight, 168
 Herbarium mould, 177
 —— of fungi, 182
 Hop disease, 167
 Hyphomycetes, 139

 Inoculation, 9
 Iris rust, 115

 _Lecythea_, 107
 —— _capræarum_, 117
 —— (Descriptions), 206
 —— _Lini_, 108
 —— _longicapsula_, 118
 —— _Rosæ_, 34, 107
 Lettuce mould, 156
 Line-like rust, 95
 Long-stemmed rust, 114
 Luzula rust, 104

 Maple blight, 169
 Meadow-saffron smut, 92
 Meadow-sweet brand, 67
 Mealy Guelder-rose blight, 172
 _Melampsora betulina_, 118
 —— (Descriptions), 213
 —— _salicina_, 117
 Mercury rust, 110
 Microscopic examination, 183
 —— fungi collecting, 179
 Microscopic preserving, 182
 _Microsphæria Berberidis_, 170
 —— (Descriptions), 219
 —— _Ehrenbergii_, 171
 —— _Hedwigii_, 172
 Mildew and brand, 45
 —— what is it?, 46
 Mint brand, 58
 —— rust, 102
 Monthly calendar of fungi, 180
 Moulds, 138
 Mould, Dock, 160
 —— Lettuce, 156
 —— Onion, 155
 —— Parsnip, 157
 —— Potato, 144
 —— Rose, 159
 —— Spinach, 158
 —— Tare, 156
 Mountain-ash cluster-cups, 19
 Mounting fungi, 184
 Mugwort blight, 174
 Mycelium, 23

 Nettle cluster-cups, 14
 Nightshade rust, 112
 Number of species, 45

 Oak-leaf rust, 111
 _Oidium_, 34, 162
 —— _leucoconium_, 167
 —— _monilioides_, 162
 —— _Tuckeri_, 164
 Onion mould, 155
 Oogonia, 129
 Oospores, 131
 Origin of mildew, 47

 Parsnip mould, 157
 Pea blight, 173
 Pear tree cluster-cups, 18
 Pea and bean rust, 114
 Pearust, germination of, 40
 Pennywort rust, 100
 _Peridermium_, 20
 —— (Descriptions), 189
 _Peridium_, 4
 _Perithecium_, 35
 Periwinkle brand, 103
 —— rust, 103
 Persicaria rust, 104
 _Peronospora_, 138
 —— (Descriptions), 215
 —— _destructor_, 156
 —— _effusa_, 159
 —— _gangliformis_, 156
 —— _infestans_, 153
 —— _macrospora_, 158
 —— _nivea_, 157
 —— _obliqua_, 160
 —— _Schleideniana_, 155
 —— _sparsa_, 159
 —— _Trifoliorum_, 157
 —— _Umbelliferarum_, 158
 —— _Viciæ_, 156
 Pepper brand, 86
 _Phragmidium_, 71
 _Phyllactinia_ (Descriptions), 218
 —— _guttata_, 168
 Pilewort rust, 115
 _Podisoma_ (Descriptions), 201
 _Polycystis_, 91
 —— (Descriptions), 211
 —— _pompholygodes_, 91
 —— _Violæ_, 92
 Potato disease, 144
 —— mould, 142, 144
 —— smut, 93
 Preserving fungi, 182
 _Puccinia_ (Descriptions), 196
 —— _Anemones_, 60
 —— _Compositarum_, 63
 —— _coronata_, 57
 —— _glechomatis_, 59
 —— _graminis_, 25
 —— _Menthæ_, 58
 —— _Rosæ_, 34
 —— _Saniculæ_, 64
 —— _Syngenesiarum_, 62
 —— _Umbelliferarum_, 64
 —— _variabilis_, 62
 —— _vincæ_, 103
 Purslane white rust, 137

 Raspberry brand, 71
 Reed smut, 83
 _Rœstelia_ (Descriptions), 189
 —— _cancellata_, 19
 —— _cornuta_, 19
 —— _lacerata_, 19
 Rose blight, 166
 —— mould, 107
 —— rust, 159
 _Rusts_, 95, 110
 Rust, Bean, 104
 —— Beet, 104
 —— Birch, 118
 —— Butter-bur, 122
 —— Cabbage, 124
 —— Campanula, 123
 —— Clover, 116
 —— Coltsfoot, 120
 —— Composite, 105
 —— Corn, 49, 95
 —— Cow-parsnip, 105
 —— Cow-wheat, 122
 —— Fern, 112
 —— Flax, 109
 —— Goatsbeard, 136
 —— Goat-willow, 116
 —— Golden-rose, 113
 —— Grass of Parnassus, 106
 —— Groundsel, 97
 —— Iris, 115
 —— Long-stemmed, 114
 —— Luzula, 104
 —— Mercury, 110
 —— Mint, 102
 —— Nightshade, 112
 —— Oak-leaf, 111
 —— Pea and Bean, 114
 —— Pennywort, 100
 —— Periwinkle, 103
 —— Persicaria, 104
 —— Pilewort, 115
 —— Rose, 107
 —— St.-John’s-wort, 113
 —— Sandspurry, 136
 —— Sedge, 104
 —— Sorrel, 111
 —— Sow-thistle, 122
 —— Stinking, 87
 —— Sweet-smelling, 99
 —— Thistle, 99
 —— Twin-faced, 111
 —— Umbellifer, 105
 —— Violet, 102
 Rye smut, 92

 Sandspurry white rust, 136
 Sanicle brand, 64
 —— cluster-cups, 14
 Sedge rust, 104
 —— smut, 84
 Smuts, 76
 Smut, Anther, 85
 —— Cocksfoot, 83
 —— Complex, 90
 —— Corn, 79
 —— Crowfoot, 91
 —— Elongated, 84
 —— Goatsbeard, 82
 —— Grass, 79
 —— Maize, 79
 —— Meadow-saffron, 92
 —— Potato, 93
 —— Reed, 83
 —— Rye, 92
 —— Sedge, 84
 —— Trientalis, 93
 —— Violet, 92
 St.-John’s-wort rust, 113
 Sow-thistle rust, 122
 Specific names, 57
 Spermatia, 24
 SPERMOGONES, 22, 98
 _Sphærotheca_ (Descriptions), 218
 —— _Castagnei_, 167
 —— _pannosa_, 167
 Spinach mould, 158
 Sporangium, 165
 Sporidia, 38
 Spurge cluster-cups, 11
 Sterigmata, 24
 Stinking rust, 87
 Strawberry brand, 72
 Stylospores, 38, 42
 Suckers, 125, 141
 SUGGESTIONS, 179
 Sweet-smelling rust, 99

 Tare mould, 156
 Thistle brand, 62
 Thistle white rust, 137
 _Tilletia caries_, 87
 —— (Descriptions), 202
 _Trichobasis Betæ_, 104
 —— _caricina_, 104
 —— _Cichoracearum_, 105
 —— (Descriptions), 207
 —— _Fabæ_, 104
 —— _hydrocotyles_, 100
 —— _Labiatarum_, 102
 —— _linearis_, 95
 —— _oblongata_, 105
 —— _Parnassiæ_, 106
 —— _Petroselini_, 105
 —— _Polygonorum_, 104
 —— _rubigo-vera_, 49, 95
 —— _Senecionis_, 97
 —— _suaveolens_, 99
 —— _Umbellatarum_, 105
 —— _Violarum_, 102
 Trientalis smut, 93
 _Triphragmium_ (Descriptions), 196
 —— _Ulmariæ_, 67
 _Tuburcinia_, 93
 —— (Descriptions), 212
 Tulasne on Fungi, 35
 Twin-faced rust, 111

 _Uncinula adunca_, 169
 —— _bicornis_, 169
 —— (Descriptions), 218
 Uredines, 33
 _Uredo Betulina_, 118
 —— _bifrons_, 111
 —— _Circææ_, 112
 —— _confluens_, 110
 —— (Descriptions), 204
 —— _Filicum_, 112
 —— _hydrocotyles_, 101
 —— _Hypericorum_, 113
 —— _Parnassiæ_, 106
 —— _Quercus_, 111
 —— _Rosæ_, 33
 _Urocystis_, 91
 _Uromyces apiculata_, 116
 —— _appendiculata_, 40, 114
 —— (Descriptions), 210
 —— _Ficariæ_, 115
 —— _Ulmariæ_, 114
 _Ustilago antherarum_, 85
 —— (Descriptions), 202
 —— _longissima_, 84
 —— _maydis_, 79
 —— _olivacea_, 84
 —— _receptaculorum_, 83
 —— _Salveii_, 84
 —— _segetum_, 79
 —— _typhoides_, 79, 83

 _Valsa suffusa_, 35
 Vine disease, 164
 Violet cluster-cups, 13
 Violet smut, 92

 Wedge-rust, Birch, 118
 —— Willow, 117
 Wheat diseases, 85
 —— mildew, 53
 White mildews or blights, 162
 _White rusts_, 124
 White rust, Cabbage, 129, 136
 —— Crucifer, 136
 —— Goatsbeard, 136
 —— Purslane, 137
 —— Sandspurry, 136
 Willow blight, 169
 —— wedge-rust, 117

 _Xenodochus carbonarius_, 73
 —— (Descriptions), 195

 Zoospores, 126


           --------------------------------------------------

       WYMAN AND SONS, PRINTERS, GREAT QUEEN STREET, LONDON, W.C.


------------------------------------------------------------------------



 ● Transcriber’s Notes:
    ○ A link to the Index was added to the Table of Contents.
    ○ The Table of Contents entry for the first Appendix has no
      identifier. Clicking on the page number will take you to Appendix
      A.
    ○ The Table of Contents references Appendix II. This is should have
      been a reference Appendix B. Clicking on the page number for
      Appendix II will take you to Appendix B.
    ○ The image of SPERMOGONES (Fig 1.) on page 25 has been rotated to
      make the letter identifications more legible.
    ○ On page 40 there is a reference to fig. 150, but nothing in that
      figure is labeled 150.
    ○ On page 56, in the footnote, there is a reference to fig. 45 on
      Plate II. This was corrected to Plate III.
    ○ On page 67 there is a reference to fig. 47 on Plate II. This was
      corrected to Plate III.
    ○ On page 69 there are references to figs. 47 and 41 on Plate II.
      This was corrected to Plate III.
    ○ On page 79 there is a reference to figs. 123—125 on Plate IV. This
      was corrected to Plate VI.
    ○ On page 216 there is a reference to fig. 268 on Plate VII. This
      was corrected to Plate XVI.
    ○ Missing or obscured punctuation was silently corrected.
    ○ Typographical errors were silently corrected.
    ○ Inconsistent spelling and hyphenation were made consistent only
      when a predominant form was found in this book.
    ○ Text that was in italics is enclosed by underscores (_italics_);
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