CHAPTER XXII.

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.

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_.

=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.

=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.

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.