CLASSIFICATION OF THE FUNGI.
=429. Classification of the fungi.=—Those who believe that the fungi
represent a natural group of plants arrange them in three large series
related to each other somewhat as follows:
The Gonidium Type or Series. The number of
gonidia in the sporangium is indefinite and
variable. It may be very large or very small,
or even only one in a sporangium. To this
series belong the lower fungi; examples: mucor,
saprolegnia, peronospora, etc.
The Basidium Type or Series. The number of
gonidia on a basidium is limited and definite,
and the basidium is a characteristic structure;
examples: uredineæ (rusts), mushrooms, etc.
The Ascus Type or Series. The number of spores
in an ascus is limited and definite, and the
ascus is a characteristic structure; examples:
leaf curl of peach (exoascus), powdery mildews,
black knot of plum, black rot of grapes, etc.
=430.= Others believe that the fungi do not represent a natural
group, but that they have developed off from different groups of
the algæ by becoming parasitic. As parasites they no longer needed
chlorophyll, and consequently lost it.
According to this view the lower fungi have developed off from the
lower algæ (saprolegnias, mucors, peronosporas, etc., being developed
off from siphonaceous algæ like vaucheria), and the higher fungi being
developed off from the higher algæ (the ascomycetes perhaps from the
Rhodophyceæ).
=431. A very general outline of classification=,[19] according to
the former of these views, might be presented here to show the general
relationships of the fungi studied, with the addition of a few more
in orders not represented above. It should be borne in mind that the
author in presenting this view of classification does not necessarily
commit himself to it. It is based on that presented in Engler &
Prantl’s Pflanzenfamilien. There are three classes.
[19] =Class Myxomycetes=, or =Mycetozoa=.—To this class belong the
“slime molds,” low organisms consisting of masses of naked protoplasm
which flows among decaying leaves and in decaying wood, coming to
the surface to fruit. The fruit in many cases resembles miniature
puff-balls, and these plants were formerly classed with the puff-balls.
The spores germinate by forming swarm spores which unite to form a
small plasmodium, which in turn grows to form a large plasmodium or
protoplasmic mass. It is doubtful if they are any more plant than
animal organisms. Examples: Trichia, Arcyria, Stemonitis, Physarum,
Ceratiomyxa, etc., on rotten wood; Plasmodiophora brassicæ is a
parasite causing club foot of cabbage, radishes, etc. It lives within
the roots, causing large knots and swellings on the same.
[Illustration: Fig. 249.
Chytrids. _A_, Harpochytrium hedenii, parasitic on spirogyra threads;
_a_, sickle-form plant; _b_, the sporangium part with escaping
zoospores; _c_, old plant proliferating by forming new sporangium
in the old empty one; _d_, zoospore; _e_, two young plants just
beginning to grow. _B_, Rhizophidium globosum parasitic on spirogyra.
Globose sporangium with delicate threads inside of the host, zoospores
escaping from one. _C_, Olpidium pendulum, parasitic in spirogyra cell.
Elliptical sporangium with slender exit tube through which zoospores
are escaping. _D_, Lagenidium rabenhorstii parasitic in spirogyra cell.
Two slender sporangia with exit tubes through which protoplasm escapes
forming a rounded mass at the end of tube, this protoplasm forming
biciliate zoospores.]
I. Class Phycomycetes (Alga-like Fungi).
1. SUBCLASS OOMYCETES.
=432.= These are the egg-spore fungi. They include the water mold
(Saprolegnia), the downy mildew of the grape (Plasmopara), the potato
blight (Phytophthora), the white rust of cruciferous plants (Cystopus
= Albugo), the damping-off fungus (Pythium), and many parasites of
the algæ known as chytrids, as Olpidium, Rhizophidium, Lagenidium,
Chytridium, etc.
The two following orders are sometimes placed in a separate subclass,
_Archimycetes_.
[Illustration: Fig. 250.
Monoblepharis insignis Thaxter. End of hypha bearing oogonium (_oog_)
and antheridium (_ant_). Sperms escaping from antheridium and creeping
up on the oogonium. (After Thaxter.)]
=433. Order Chytridiales (Chytridineæ).=—These include the lowest
fungi. Many of them are parasitic on algæ and lack mycelium, the
swarm spore either with or without minute rhizoids, developing into
a globose sporangium (Rhizophidium, Chytridium, Olpidium, etc., fig.
249), or the swarm spore attached to the wall of the host develops into
a long sword-shaped body with a sterile base, which proliferates and
forms a new sporangium in the old one (Harpochytrium), or with slight
development of mycelium in aquatic plants (Cladochytrium). Some are
parasitic in leaves and stems of land plants. Synchytrium decipiens is
very common on the trailing legume, Amphicarpæa monoica.
=434. Order Ancylistales (Ancylistineæ).=—The members of this
order have a slight development of mycelium and many are parasitic in
algæ (Lagenidium, fig. 249).
=435. Order Saprolegniales (Saprolegniineæ).=—These include the
water molds (Saprolegnia). See Chapter XIX.
=436. Order Monoblepharidales (Monoblepharidineæ).=—These are
peculiar water molds, related to the Saprolegniales, but motile sperm
cells are formed (Monoblepharis, etc., fig. 250).
=437. Order Peronosporales (Peronosporineæ).=—These include the
downy mildews (Peronospora, Plasmopara, Phytopthora, etc.), and the
white rust of crucifers and other plants (Cystopus = Albugo), Chapter
XIX.
2. SUBCLASS ZYGOMYCETES.
=438.= These are the conjugating fungi.
=439. Order Mucorales (Mucorineæ).=—This includes the black mold
and its many relatives (Mucor, Rhizopus, etc.). Chapter XIX.
=440. Order Entomophthorales (Entomophthorineæ).=—This order
includes the “fly fungus” (Empusa) and its many relatives parasitic on
insects. In the autumn and winter dead flies are often found stuck to
window-panes, with a white ring of the conidia around each fly.
II. Class Ascomycetes. (The ascus series.)
1. SUBCLASS HEMIASCOMYCETES.
[Illustration: Fig. 251.
Dipodascus albidus. _A_, thread with sexual organs, ascogonium and
antheridium; _B_, fertilized ascogonium developing ascus; _C_, ascus
with spores; _D_, conidia. (After Lagerheim.)]
=441. Order Hemiascales (Hemiascineæ).=—Fungi with a well
developed, septate mycelium, but with a sporangium-like ascus, i.e.,
a large and indefinite number of spores in the ascus. Examples:
Protomyces macrosporus in stems of Umbelliferæ, or P. polysporus in
Ambrosia trifida. These two are by some placed in the Ustilagineæ.
Dipodascus albidus grows in the exuding sap of Bromeliaceæ in Brazil
and the sap of the beech in Sweden. The ascus is developed as the
result of the fertilization of an ascogonium with an antheridium (see
fig. 251).
2. SUBCLASS PROTOASCOMYCETES.
=442. The asci are well-defined= and usually with a limited and
definite number of spores (usually 8, sometimes 1, 2, 4, 16, or more).
Mycelium often well developed and septate. Asci scattered on the
mycelium, not associated in definite fields or groups.
=443. Order Protoascales (Protoascineæ).=—The asci are separate
cells, or are scattered irregularly in loose wefts of mycelium.
No fruit body. (The yeast, Saccharomyces, see paragraph 237; and
certain mold-like fungi, some of which are parasitic on mushrooms, as
Endomyces, are examples.)
3. SUBCLASS EUASCOMYCETES.
Asci associated in surfaces forming a hymenium, or in groups or
intermingled in the elements of a fruit body. Fruit body usually
present.
The following four or five orders comprise the Discomycetes, according
to the usual classification.
=444. Order Protodiscales (Protodiscineæ).=—The asci are exposed
and form large and indefinite groups, but there is no definite fruit
body. Examples: leaf curl of peach, plum pocket, etc. (Exoascus).
=445. Order Helvellales (Helvellineæ).=—The asci form large
fields over the upper portion of the fruit body. This order includes
the morels (fig. 231_a_), helvellas, earth tongues (Geoglossum), etc.
=446. Order Pezizales (Pezizineæ).=—The asci form a definite
field or fruiting surface surrounded on the sides and below by a wall
of fungus tissue, forming a fruit body in the shape of a cup. These are
known as the cup fungi (Peziza, Lachnea, etc.).
=447. Order Phacidiales (Phacidiineæ).=—Fungi mostly saprophytic,
and fruit body similar to the cup fungi. Examples: Propolis in rotting
wood, Rhytisma forming black crusts on leaves (maple for example),
Urnula craterium, a large black beaker-shaped fungus on the ground.
=448. Order Hysteriales (Hysteriineæ).=—Fungi with a more or less
elongated fruit body with an enclosing wall opening by a long slit. In
some forms the fruit body has the appearance of a two-lipped body; in
others it is shaped like a clam shell, the asci being inside. Example,
Hysterographium common on dry, dead, decorticated sticks.
=449. Order Tuberales (Tuberineæ).=—The more or less rounded
fruit bodies are usually subterranean. The most important fungi in this
order are the truffles (Tuber). The mycelium of many species assists
in the formation of mycorhiza on the roots of oaks, etc., and several
species are partly cultivated, or protected, and collected for food.
This is especially the case with Tuber brumale and its forms; more than
a million francs worth of truffles are sold in France and Italy yearly.
Dogs and pigs are employed in the collection of truffles from the
ground.
=450. Order Plectascales (Plectascineæ).=—The fruit body of these
plants is more or less globose, and contains the asci distributed
irregularly through the mycelium of the interior. Some are subterranean
(Elaphomyces), while others grow in decaying plants, or certain food
substances (Eurotium, Sterigmatocystis, Penicillium). Penicillium in
its conidial stage forms blue mold on fruit, bread, etc.
The following four orders comprise the Pyrenomycetes, according to the
usual classification.
=451. Order Perisporiales.=—The powdery mildews are good examples
of this order (Uncinula, Microsphæra, etc., Chapter XXI).
=452. Order Hypocreales.=[20]—The fruit bodies are colorless,
or bright colored and entirely enclose the asci, sometimes opening
by an apical pore. Nectria cinnabarina has clusters of minute orange
oval fruit bodies, and is common on dead twigs. Cordyceps with a
number of species is parasitic on insects, and on certain subterranean
Ascomycetes, especially Elaphomyces (of the order _Plectascales_ =
_Plectascineæ_).
=453. Order Dothidiales.=[21]—Fungi with black stroma formed of
mycelium in which are cavities containing the asci. The cavities are
usually shaped like a perithecium, but there is no wall distinct from
the tissue of the stroma (Dothidea, Phyllachora, on grasses).
=454. Order Sphæriales.=[22]—These contain the so-called black
fungi, with separate or clustered, oval, fruit bodies, black in color.
The black wall encloses the asci, and usually opens by an apical pore.
Examples are found in the black knot of plum and cherry, black rot of
grapes, and in Rosellinia, Hypoxylon, Xylaria, etc., on dead wood.
=455. Order Laboulbeniales (Laboulbineæ).=—These are peculiar
fungi attached to the legs and bodies of insects by a short stalk, and
provided with a sac-like fruit body which contains the asci. Example,
Laboulbenia.
III. Class Basidiomycetes. (The basidium series.)
1. SUBCLASS HEMIBASIDIOMYCETES.
=456. Order Ustilaginales (Ustilagineæ).=—This order includes the
well-known smuts on corn, wheat, oats, etc. (Ustilago, Tilletia, etc.).
2. SUBCLASS ÆCIDIOMYCETES.
=457. Order Uredinales=[23] (Uredineæ).—This order includes the
parasitic fungi known as rusts. Examples: wheat rust (Chapter XX), the
cedar apple, etc.
The true Basidiomycetes include the following orders:
3. SUBCLASS PROTOBASIDIOMYCETES.
=458. Order Auriculariales.=[24]—This order includes trembling
fungi in which the basidium is long and divided transversely into
usually four cells (example, Auricularia), and similar forms. Pilacre
petersii on dead wood represents an angiocarpous form.
=459. Order Tremellales (Tremellineæ)=, trembling or gelatinous
fungi with the globose basidium divided longitudinally into four cells
(Tremella).
4. SUBCLASS EUBASIDIOMYCETES.
=460. Order Dacryomycetales (Dacryomycetineæ).=—This order
includes certain fungi of a gelatinous or waxy consistency, usually
of bright colors. They resemble the Tremellales, but the basidia are
slender and fork into two long sterigmata. (Example, Dacryomyces.)
Gyrocephalus rufus is quite a large plant, 10-15 cm. high, growing on
the ground in woods.
=461. Order Exobasidiales (Exobasidiineæ).=—The fungus causing
azalea apples is an example (Exobasidium).
=462. Order Hymeniales (Hymenomycetineæ).=—In this order the
basidia are usually club-shaped and undivided, and bear usually four
spores on the end (sometimes two or six). There are several families.
=463. Family Thelephoraceæ.=—The fruit bodies are more or less
membranous and spread over wood or the ground, or somewhat leaf-like,
growing on wood or the ground. The fruiting surface is nearly or quite
even, and occupies the under side of the leaf-like bodies (Stereum,
Thelephora) or the outside of the forms spread out on wood (Corticium,
Coniophora).
=464. Family Clavariaceæ.=—This order includes the fairy clubs,
and some of the coral fungi. The larger number of species are in one
genus (Clavaria, fig. 248).
=465. Family Hydnaceæ.=—The fungi of this order are known as
“hedgehog” fungi, because of the numerous awl-like teeth or spines over
which the fruiting surface is spread, as in Hydnum (figs. 246, 247).
=466. Family Polyporaceæ.=—The tube-bearing fungi (Polyporus,
Boletus, etc., fig. 245).
=467. Family Agaricaceæ.=—The gill-bearing fungi (Agaricus,
Amanita, etc., see Chapter XXI).
The above five orders, according to the earlier classification (still
used at the present time by some), made up the order Hymenomycetes,
while the following five orders made up the Gasteromycetes. The
Hymenomycetes, according to this system, included those plants in which
the fruiting portion (hymenium) is either exposed from the first, or
if covered by a veil or volva (as in Agaricus, Amanita, etc.) this
ruptures and exposes the fruiting surface before, or at the time of,
the ripening of the spores, while the Gasteromycetes included those in
which the fruit body is closed until after the maturity of the spores.
=468. Order Phallales (Phallineæ).=—The “stink-horn” fungi, or
“buzzard’s nose.” Usually foul-smelling fungi, the fruiting portion
borne aloft on a stout stalk, and dissolving (Dictyophora, Ithyphallus,
etc.).
=469. Order Hymenogastrales (Hymenogastrineæ).=—The basidia form
a distinct hymenium which does not break down at maturity. Some of
the plants resemble Boletus or Agaricus in the way the fruit bodies
open (Secotium, etc.), while others open irregularly on the surface
(Rhizopogon) or like an earth star (Sclerogaster), or portions of the
surface become gelatinized (Phallogaster). The last-named one grows on
very rotten wood, while most of the others grow on the ground.
=470. Order Lycoperdales (Lycoperdineæ).=—These include the
“puff-balls,” or “devil’s snuff-box” (Lycoperdon), and the earth stars
(Geaster). The basidia form a distinct hymenium, but at maturity the
entire inner portion of the plant (except certain peculiar threads, the
capillitium) disintegrates and with the spores forms a powdery mass.
=471. Order Nidulariales (Nidulariineæ).=—These are known
as bird-nest fungi. The fruit body when mature is cup-shaped,
or goblet-shaped, and contains minute flattened circular bodies
(peridiola) containing the spores. The intermediate portions of the
fruit body disintegrate and set the peridiola free, which then lie in
the cup-shaped base like eggs in a nest.
=472. Order Plectobasidiales (Plectobasidiineæ).=—The basidia
do not form a definite hymenium, but are interwoven with the threads
inside, or are collected into knot-like groups. (Examples: Calostoma,
Tulostoma, Astræus, Sphærobolus, etc.)
=472a. Lichens.=—The plant body of the lichens (see paragraphs
200, 201) consists of two component parts, the one a fungus, the other
an alga. The fructification is that of the fungus. The fruit body
shows the lichens to be related some to the Ascomycetes, others to
the Hymenomycetes, and Gasteromycetes. They are usually classified as
a distinct class or order from the fungi, but a natural arrangement
would distribute them in several of the orders above. Their special
relationship with these orders has not been satisfactorily worked out.
For the present they are arranged as follows:
=Ascolichenes.=
_Pyrenocarpous lichens_ (those with a fruit body like the
Pyrenomycetes).
_Gymnocarpous lichens_ (those with a fruit body like the Discomycetes).
=Hymenolichenes= (those with a fruit body like the Hymenomycetes).
=Gasterolichenes= (those with a fruit body like the
Gasteromycetes).
From a vegetative standpoint there are two types according to the
distribution of the elements.
1st. Where the fungal and algal elements are evenly distributed in the
plant body the lichen is said to be _homoiomerous_. There are two types
of these:
_a. Filamentous lichens_, example, Ephebe pubescens.
_b. Gelatinous lichens_, example, Collema (with the alga nostoc),
Physma (with the Chroococcaceæ).
2d. Where the elements are stratified, as in Parmelia, etc., the lichen
is said to be _heteromerous_. In these there are three types:
_a. Crustaceous lichens_, the plant body is in the form of a thin
incrustation on rocks, etc.
_b. Foliaceous lichens_, the plant body is leaf-like and lobed and more
or less loosely attached by rhizoids: Parmelia, Peltigera, etc.
_c. Fruticose lichens_, the plant body is filamentous or band-like and
branched, as in Usnea, Cladonia, etc.
[Illustration: Fig. 251_a_. Rock lichen (Parmelia contigua).]
FOOTNOTES:
[20] As suborder in Engler and Prantl.
[21] As suborder in Engler and Prantl.
[22] As suborder in Engler and Prantl.
[23] The Uredinales and Auriculariales in Engler and Prantl are placed
in order, Auriculariineæ.
[24] The Uredinales and Auriculariales in Engler and Prantl are placed
in order, Auriculariineæ.