of _Agaricus cirrhatus_.
[K] Currey, "On Development of _Sclerotium roseum_," in "Journ. Linn.
Soc." vol. i. p. 148.
[L] Currey, in "Linn. Trans." xxiv. pl. 25, figs. 17, 26.
[M] Berkeley, "On Two Tuberiform Veg. Productions from Travancore,"
in "Trans. Linn. Soc." vol. xxiii. p. 91.
[N] Berkeley, "On a Peculiar Form of Mildew in Onions," "Journ. Hort.
Soc." vol. iii p. 91.
[O] De Bary, "Ann. des Sci. Nat." 4th series, vol. xx.
XIII.
GEOGRAPHICAL DISTRIBUTION.
Unfortunately no complete or satisfactory account can be given of the
geographical distribution of fungi. The younger Fries,[A] with all the
facilities at his disposal which the lengthened experience and large
collections of his father afforded, could only give a very imperfect
outline, and now we can add very little to what he has given. The
cause of this difficulty lies in the fact that the Mycologic Flora of
so large a portion of the world remains unexplored, not only in remote
regions, but even in civilized countries where the Phanerogamic Flora
is well known. Europe, England, Scotland, and Wales are as well
explored as any other country, but Ireland is comparatively unknown,
no complete collection having ever been made, or any at least
published. Scandinavia has also been well examined, and the northern
portions of France, with Belgium, some parts of Germany and Austria,
in Russia the neighbourhood of St. Petersburg, and parts of Italy and
Switzerland. Turkey in Europe, nearly all Russia, Spain, and Portugal
are almost unknown. As to North America, considerable advances have
been made since Schweinitz by Messrs. Curtis and Ravenel, but their
collections in Carolina cannot be supposed to represent the whole of
the United States; the small collections made in Texas, Mexico, etc.,
only serve to show the richness of the country, not yet half
exhausted. It is to be hoped that the young race of botanists in the
United States will apply themselves to the task of investigating the
Mycologic Flora of this rich and fertile region. In Central America
very small and incomplete collections have as yet been made, and the
same may be said of South America and Canada. Of the whole extent of
the New World, only the Carolina States of North America can really be
said to be satisfactorily known. Asia is still less known, the whole
of our vast Indian Empire being represented by the collections made by
Dr. Hooker in the Sikkim Himalayas, and a few isolated specimens from
other parts. Ceylon has recently been removed from the category of the
unknown by the publication of its Mycologic Flora.[B] All that is
known of Java is supplied by the researches of Junghuhn; whilst all
the rest is completely unknown, including China, Japan, Siam, the
Malayan Peninsula, Burmah, and the whole of the countries in the north
and west of India. A little is known of the Philippines, and the
Indian Archipelago, but this knowledge is too fragmentary to be of
much service. In Africa no part has been properly explored, with the
exception of Algeria, although something is known of the Cape of Good
Hope and Natal. The Australasian Islands are better represented in the
Floras published of those regions. Cuba and the West Indies generally
are moderately well known from the collections of Mr. C. Wright, which
have been recorded in the journal of the Linnæan Society, and in the
same journal Mr. Berkeley has described many Australian species.
It will be seen from the above summary how unsatisfactory it must be
to give anything like a general view of the geographical distribution
of fungi, or to estimate at all approximately the number of species on
the globe. Any attempt, therefore, must be made and accepted subject
to the limitations we have expressed.
The conditions which determine the distribution of fungi are not
precisely those which determine the distribution of the higher plants.
In the case of the parasitic species they may be said to follow the
distribution of their foster-plants, as in the case of the rust, smut,
and mildew of the cultivated cereals, which have followed those
grains wherever they have been distributed, and the potato disease,
which is said to have been known in the native region of the potato
plant before it made its appearance in Europe. We might also allude to
_Puccinia malvacearum_, Ca., which was first made known as a South
American species; it then travelled to Australia, and at length to
Europe, reaching England the next year after it was recorded on the
Continent. In the same manner, so far as we have the means of knowing,
_Puccinia Apii_, Ca., was known on the Continent of Europe for some
time before it was detected on the celery plants in this country.
Experience seems to warrant the conclusion that if a parasite affects
a certain plant within a definite area, it will extend in time beyond
that area to other countries where the foster-plant is found. This
view accounts in some part for the discovery of species in this
country, year after year, which had not been recorded before; some
allowance being made for the fact that an increased number of
observers and collectors may cause the search to be more complete, yet
it must be conceded that the migration of Continental species must to
some extent be going on, or how can it be accounted for that such
large and attractive fungi as _Sparassis crispa_, _Helvellas gigas_,
and _Morchella crassipes_ had never been recorded till recently, or
amongst parasitic species such as the two species of _Puccinia_ above
named? In the same manner it is undoubtedly true that species which at
one time were common gradually become somewhat rare, and at length
nearly extinct. We have observed this to apply to the larger species
as well as to the microscopic in definite localities. For instance,
_Craterellus cornucopioides_ some ten years ago appeared in one wood,
at a certain spot, by hundreds, whereas during the past three or four
years we have failed to find a single specimen. As many years since,
and in two places, where the goat's-beard was abundant, as it is now,
we found nearly half the flowering heads infested with _Ustilago
receptaculorum_, but for the past two or three years, although we have
sought it industriously, not a single specimen could be found. It is
certain that plants found by Dickson, Bolton, and Sowerby, have not
been detected since, whilst it is not improbable that species common
with us may be very rare fifty years hence. In this manner it would
really appear that fungi are much more liable than flowering plants to
shift their localities, or increase and diminish in number.
The fleshy fungi, _Agaricini_ and _Boleti_ especially, are largely
dependent upon the character of woods and forests. When the
undergrowth of a wood is cleared away, as it often is every few years,
it is easy to observe a considerable difference in the fungi. Species
seem to change places, common ones amongst a dense undergrowth are
rare or disappear with the copsewood, and others not observed before
take their place. Some species, too, are peculiar to certain woods,
such as beech woods and fir woods, and their distribution will
consequently depend very much on the presence or absence of such
woods. Epiphytal species, such as _Agaricus ulmarius_, _Agaricus
mucidus_, and a host of others, depend on circumstances which do not
influence the distribution of flowering plants. It may be assumed that
such species as flourish in pastures and open places are subject to
fewer adverse conditions than those which affect woods and forests.
Any one who has observed any locality with reference to its Mycologic
Flora over a period of years will have been struck with the difference
in number and variety caused by what may be termed a "favourable
season," that is, plenty of moisture in August with warm weather
afterwards. Although we know but little of the conditions of
germination in Agarics, it is but reasonable to suppose that a
succession of dry seasons will considerably influence the flora of any
locality. Heat and humidity, therefore, are intimately concerned in
the mycologic vegetation of a country. Fries has noted in his essay
the features to which we have alluded. "The fact," he says, "must not
be lost sight of that some species of fungi which have formerly been
common in certain localities may become, within our lifetime, more and
more scarce, and even altogether cease to grow there. The cause of
this, doubtless, is the occurrence of some change in the physical
constitution of a locality, such as that resulting from the
destruction of a forest, or from the drainage, by ditches and
cuttings, of more or less extensive swamps, or from the cultivation of
the soil--all of them circumstances which cause the destruction of the
primitive fungaceous vegetation and the production of a new one. If we
compare the fungal flora of America with that of European countries,
we observe that the former equals, in its richness and the variety of
its forms, that of the phanerogamous flora; it is probable, however,
that, in the lapse of more or fewer years, this richness will
decrease, in consequence of the extension of cultivation--as is
illustrated, indeed, in what has already taken place in the more
thickly peopled districts, as, for example, in the vicinity of New
York."
Although heat and humidity influence all kinds of vegetation, yet heat
seems to exert a less, and humidity a greater, influence on fungi than
on other plants. It is chiefly during the cool moist autumnal weather
that the fleshy fungi flourish most vigorously in our own country, and
we observe their number to increase with the humidity of the season.
Rain falls copiously in the United States, and this is one of the most
fruitful countries known for the fleshy fungi. Hence it is a
reasonable deduction that moisture is a condition favourable to the
development of these plants. The _Myxogastres_, according to Dr. Henry
Carter, are exceedingly abundant--in individuals, at least, if not in
species--in Bombay, and this would lead to the conclusion that the
members of this group are influenced as much by heat as humidity in
their development, borne out by the more plentiful appearance of the
species in this country in the warmer weather of summer.
In the essay to which we have alluded, Fries only attempts the
recognition of two zones in his estimate of the distribution of fungi,
and these are the temperate and tropical. The frigid zone produces no
peculiar types, and is poor in the number of species, whilst no
essential distinction can be drawn between the tropical and
sub-tropical with our present limited information. Even these two
zones must not be accepted too rigidly, since tropical forms will in
some instances, and under favourable conditions, extend far upwards
into the temperate zone.
"In any region whatever," writes Fries, "it is necessary, in the first
instance, to draw a distinction between its open naked plains and
its wooded tracts. In the level open country there is a more rapid
evaporation of the moisture by the conjoined action of the sun and
wind; whence it happens that such a region is more bare of fungi
than one that is mountainous or covered by woods. On the other hand,
plains possess several species peculiar to themselves; as, for
example, _Agaricus pediades_, certain _Tricholomata_, and, above
all, the family _Coprini_, of which they may be regarded as the
special habitat. The species of this family augment in number, in
any given country, in proportion to the extent and degree of its
cultivation; for instance, they grow more luxuriantly in the
province of Scania, in Sweden--a district farther distinguished
above all others by its cultivation and fertility. In well-wooded
countries moisture is retained a much longer time, and, as a
result, the production of fungi is incomparably greater; and it is
here desirable to make a distinction between the fungi growing in
forests of resinous-wooded trees (_Coniferæ_) and those which
inhabit woods of other trees, for these two descriptions of forests
may be rightly regarded, as to their fungaceous growths, as two
different regions. Beneath the shade of _Coniferæ_, fungi are
earlier in their appearance; so much so, that it often happens they
have attained their full development when their congeners in forests
of non-resinous trees have scarcely commenced their growth. In woods
of the latter sort, the fallen leaves, collected in thick layers, act
as an obstacle to the soaking of moisture into the earth, and
thereby retard the vegetation of fungi; on the other hand, such
woods retain moisture longer. These conditions afford to several
large and remarkable species the necessary time for development. The
beech is characteristic of our own region, but, further north this
tree gives place to the birch. Coniferous woods are, moreover,
divisible into two regions--that of the pines and that of the firs.
The latter is richer in species than the former, because, as is well
known, fir-trees flourish in more fertile and moister soils.
Whether, with respect to the South of Europe, other subdivisions into
regions are required, we know not; still less are we able to
decide on the like question in reference to the countries beyond
Europe."[C]
In very cold countries the higher fungi are rare, whilst in tropical
countries they are most common at elevations which secure a temperate
climate. In Java, Junghuhn found them most prolific at an elevation of
3,000 to 5,000 feet; and in India, Dr. Hooker remarked that they were
most abundant at an elevation of 7,000 to 8,000 feet above the sea
level.
For the higher fungi we must be indebted to the summary made by Fries,
to which we have little to add.
The genus _Agaricus_ occupies the first place, and surpasses, in the
number of species, all the other generic groups known. It appears,
from our present knowledge, that the _Agarici_ have their geographic
centre in the temperate zone, and especially in the colder portion of
that zone. It is a curious circumstance that all the extra-European
species of this genus _Agaricus_ may be referred to various European
subgenera.
In tropical countries it appears that the _Agarici_ occupy only a
secondary position in relation to other genera of fungi, such as
_Polyporus_, _Lenzites_, etc. North America, on the other hand, is
richer in species of _Agaricus_ than Europe; for whilst the majority
of typical forms are common to both continents, America further
possesses many species peculiar to itself. In the temperate zone, so
close is the analogy prevailing between the various countries in
respect to the _Agaricini_, that from Sweden to Italy, and as well in
England as North America, the same species are to be found. Of 500
_Agaricini_ met with in St. Petersburg, there are only two or three
which have not been discovered in Sweden; and again, of fifty species
known in Greenland, there is not one that is not common in Sweden. The
same remarks hold good in reference to the _Agaricini_ of Siberia,
Kamtschatka, the Ukraine, etc. The countries bordering upon the
Mediterranean possess, however, several peculiar types; and Eastern
and Western Europe present certain dissimilarities in their Agaric
inhabitants. Several species, for example, of _Armillaria_ and
_Tricholoma_, which have been found in Russia, have been met with in
Sweden only in Upland, that is, in the most eastern province; all the
species which belong to the so-called _abiegno-rupestres_ and
_pineto-montanæ_ regions of Sweden are wanting in England; and it is
only in Scotland that the species of northern mountainous and
pine-bearing regions are met with--a circumstance explicable from the
similarity in physical features between Sweden and the northern
portions of Great Britain.
The species of _Coprinus_ appear to find suitable habitats in every
quarter of the globe.
The _Cortinariæ_ predominate in the north; they abound in Northern
latitudes, especially on wooded hills; but the plains offer also some
peculiar species which flourish during the rainy days of August and
September. In less cold countries they are more scarce or entirely
absent. The species of the genus _Hygrophorus_ would at first seem to
have a similar geographical distribution to those of the last group;
but this is really not the case, for the same _Hygrophori_ are to be
found in nearly every country of Europe, and even the hottest
countries (and those under the equator) are not destitute of
representatives of this wide-spread genus.
The _Lactarii_, which are so abundant in the forests of Europe and
North America, appear to grow more and more scarce towards both the
south and north. The same may be stated in regard to _Russula_.
The genus _Marasmius_ is dispersed throughout the globe, and
everywhere presents numerous species. In inter-tropical countries they
are still more abundant, and exhibit peculiarities in growth which
probably might justify their collection into a distinct group.
The genera _Lentinus_ and _Lenzites_ are found in every region of the
world; their principal centre, however, is in hot countries, where
they attain a splendid development. On the contrary, towards the north
they rapidly decrease in number.
The _Polypori_ constitute a group which, unlike that of the Agarics,
especially belongs to hot countries. The _Boleti_ constitute the only
exception to this rule, since they select the temperate and frigid
zones for their special abode, and some of them at times find their
way to the higher regions of the Alps. No one can describe the
luxuriance of the torrid zone in _Polypori_ and _Trametes_, genera of
_Hymenomycetes_, which flourish beneath the shade of the virgin
forests, where perpetual moisture and heat promote their vegetation
and give rise to an infinite variety of forms. But though the genus
_Polyporus_, which rivals _Agaricus_ in the number of its species,
inhabits, in preference, warm climates at large, it nevertheless
exhibits species peculiar to each country. This arises from the
circumstance that the _Polypori_, for the most part, live upon trees,
and are dependent on this or that particular tree for a suitable
habitat; and the tropical flora being prolific in trees of all kinds,
a multitude of the most varied forms of these fungi is a necessary
consequence. _Hexagona_, _Favolus_, and _Laschia_ are common in
inter-tropical countries, but they are either entirely absent or
extremely rare in temperate climes.
When the majority of the species of a genus are of a fleshy
consistence, it may generally be concluded that that genus belongs to
a Northern region, even if it should have some representatives in
lands which enjoy more sunshine. Thus the _Hydna_ are the principal
ornaments of Northern forests, where they attain so luxuriant a growth
and beauty that every other country must yield the palm to Sweden in
respect to them. In an allied genus, that of _Irpex_, the texture
assumes a coriaceous consistence, and we find its species to be more
especially inhabitants of warm climates.
Most of the genera of _Auricularini_ are cosmopolitan, and the same is
true of some species of _Stereum_, of _Corticium_, etc., which are met
with in countries of the most different geographical position. In
tropical countries, these genera of fungi assume the most curious and
luxuriant forms. The single and not considerable genus _Cyphella_
appears to be pretty uniformly distributed over the globe. The
_Clavariæi_ are equally universal in their diffusion, although more
plentiful in the north; however, the genus _Pterula_ possesses several
exotic forms, though in Europe it has but two representative species.
That beautiful genus of _Hymenomycetes_, _Sparassis_, occupies a
similar place next the _Clavariæi_, and is peculiarly a production of
the temperate zone and of the coniferous region.
The fungi which constitute the family of _Tremellini_ prevail in
Europe, Asia, and North America, and exhibit no marked differences
amongst themselves, notwithstanding the distances of the several
countries apart. It must, however, be stated that the _Hirneolæ_ for
the most part inhabit the tropics.
We come now to the _Gasteromycetes_--an interesting family, which
exhibits several ramifications or particular series of developments.
The most perfect _Gasteromycetes_ almost exclusively belong to the
warmer division of the temperate, and to the tropical zone, where
their vegetation is the most luxuriant. Of late the catalogue of these
fungi has been greatly enriched by the addition of numerous genera and
species, proper to hot countries, previously unknown. Not uncommonly,
the exotic floras differ from ours, not merely in respect of the
species, but also of the genera of _Gasteromycetes_. It must, besides,
be observed that this family is rich in well-defined genera, though
very poor in distinct specific forms. Among the genera found in
Europe, many are cosmopolitan.
The _Phalloidei_ present themselves in the torrid zone under the most
varied form and colouring, and comprise many genera rich in species.
In Europe their number is very restricted. As we advance northward
they decrease rapidly, so that the central districts of Sweden possess
only a single species, the _Phallus impudicus_, and even this solitary
representative of the family is very scarce. In Scania, the most
southern province of Sweden, there is likewise but one genus and one
species belonging to it, viz., the _Mutinus caninus_. Among other
members of the _Phalloidei_, may be further mentioned the _Lysurus_ of
China, the _Aseröe_ of Van Diemen's Land, and the _Clathrus_, one
species of which, _C. cancellatus_, has a very wide geographical
range; for instance, it is found in the south of Europe, in Germany,
and in America; it occurs also in the south of England and the Isle of
Wight; whereas the other species of this genus have a very limited
distribution.
The _Tuberacei_[D] are remarkable amongst the fungi in being all of
them more or less hypogeous. They are natives of warm countries, and
are distributed into numerous genera and species. The _Tuberacei_
constitute in Northern latitudes a group of fungi very poor in
specific forms. The few species of the _Hymenogastres_ belonging to
Sweden, with the exception of _Hyperrhiza variegata_ and one example
of the genus _Octaviana_, are confined to the southern provinces. The
greater part of this group, like the _Lycoperdacei_, are met with in
the temperate zone. Most examples of the genus _Lycoperdon_ are
cosmopolitan.
The _Nidulariacei_ and the _Trichodermacei_ appear to be scattered
over the globe in a uniform manner, although their species are not
everywhere similar. The same statement applies to the _Myxogastres_,
which are common in Lapland, and appear to have their central point of
distribution in the countries within the temperate zone. At the same
time, they are not wanting in tropical regions, notwithstanding that
the intensity of heat, by drying up the mucilage which serves as the
medium for the development of their spores, is opposed to their
development.[E]
Of the _Coniomycetes_, the parasitic species, as the _Cæomacei_, the
_Pucciniei_, and the _Ustilagines_, accompany their foster-plants into
almost all regions where they are found; so that smut, rust, and
mildew are as common on wheat and barley in the Himalayas and in New
Zealand as in Europe and America. _Ravenelia_ and _Cronartium_ only
occur in the warmer parts of the temperate zone, whilst _Sartvellia_
is confined to Surinam. Species of _Podisoma_ and _Roestelia_ are as
common in the United States as in Europe, and the latter appears also
at the Cape and Ceylon. Wherever species of _Sphæria_ occur there the
_Sphæronemei_ are found, but they do not appear, according to our
present knowledge, to be so plentiful in tropical as in temperate
countries. The _Torulacei_ and its allies are widely diffused, and
probably occur to a considerable extent in tropical countries.