Part 33

Hormonyces Bon. Ditiola Fries. Apyrenium Fries.

BREFIELD'S CLASSIFICATION OF FUNGI.

A system of classification of fungi which is receiving attention from mycologists is that recently presented by the distinguished German author Dr. Oscar Brefield. Dr. Brefield's exhaustive investigations into the life-history of fungi in general have been such as to entitle his views to consideration, although the system presents some inconsistencies which may prevent its adoption in its entirety.

According to the Brefield system, as summarized by his colleague Dr. Von Tavel, Fungi are divided into two primary classes: (1) the Phycomycetes, or lower fungi nearest like the algae, consisting of a one-celled thallus with sexual as well as non-sexual modes of reproduction, and (2) the Mesomycetes and the Mycomycetes, having a divided or many celled thallus, propagated by non-sexually formed spores. The Phycomycetes are further divided into two large sections, based on their methods of reproduction, termed, respectively, Zygomycetes and Oomycetes. These include the old typical Mucors, the Peronosporeae or "rotting moulds," once classed with the Hyphomycetes, the Saprolegniaceae, "Fish Moulds," of aquatic habit, the Entomophthoraceae, "Insect Moulds," together with some minor groups. The Mesomycetes connect the Phycomycetes with the Mycomycetes. The class Mycomycetes is primarily divided into two sections, viz., Ascomycetes and Basidiomycetes, with the Ustilagineae, "Smut Fungi," in Mesomycetes, forming a transitional group between Phycomycetes and the Basidiomycetal group of the higher fungi.

The Ascomycetes are primarily subdivided into Exoasci and Carpoasci, groups based on the character of the asci. In the first, Exoasci, the asci are naked and borne directly on the mycelium; in the second, Carpoasci, they are enclosed in a wrapper composed of fertile hyphae and sterile threads, having also accessory fruit forms. The first includes Endomycetes and Taphrineae. In the second are included the groups Gymnoasci, Perisporaceae, Pyrenomycetes, Hysteriaceae, Discomycetes, and Helvellaceae.

The Basidiomycetes characterized by the possession of basidia are arranged in two groups, based on the character of the basidia: (1) the Protobasidiomycetes, in which the basidia are septate, divided, and (2) the Autobasidiomycetes, in which the basidia are not divided, and bear a definite number of spores.

The first of these (Protobasidiomycetes) includes the following distinct groups: (1) the Uredineae, "Rust Fungi," which have horizontally divided basidia, always free, never enclosed; (2) the Auricularieae, having basidia somewhat resembling those of the Uredineae, but which are borne in fruit bodies with open hymenia; (3) Pileacreae, having horizontal septate basidia in closed receptacles; and (4) Tremellineae, having vertically divided basidia borne in gymnocarpous receptacles--that is, those in which the hymenium is exposed while the spores are growing.

The Autobasidiomycetes are characterized by undivided basidia, bearing spores only at the apex. This group is subdivided into three sections: (1) Dacryomycetes, which includes the lowest of the Tremelloid forms, with club-shaped basidia, nearly approaching the true Hymenomycetal type, together with several groups of minor import; (2) Gasteromycetes; and (3) Hymenomycetes, with Phalloideae placed in the group as a subsection of Gasteromycetes.

The above can only be considered as a very brief abstract of the system of classification proposed by Dr. Brefield, but it will serve to give some idea of the principle on which the system is based, which is sufficient for our present purpose. Those who wish to study the system in detail will find it treated in a comprehensive manner in Dr. Von Tavel's summary as it appears in the Vergleichende Morphologie der Pilze, Jena, 1892.

CONIOMYCETES AND HYPHOMYCETES.

In the original classification of Fries two of the primary divisions of the sporiferous Fungi were termed, respectively, Coniomycetes and Hyphomycetes. This arrangement was accepted by Berkeley, the term Coniomycetes being applied to all fungi in which the naked spores, appearing like an impalpable dust, were the principal feature of the plant, and the term Hyphomycetes to fungi in which the threads or hyphae bearing the spores were the most conspicuous feature.

Coniomycetes, as broadly interpreted by Berkeley and other mycologists of his day, included the Uredineae or "rust fungi," the Ustilagines or "smut fungi," the Sphaeropsideae, and the Melanconieae. This arrangement was very unsatisfactory on account of the distinctively different character of the methods of reproduction of the respective groups, and they have since been disassociated and by some authors ranked as distinct orders or families. Others combine Uredinei and Ustilaginei in one group under the name Hypodermei.

Familiar examples of Uredinei are seen in the rust of the Barberry leaf, etc., and of the Ustilaginei in the "smut" of corn and the "bunt" of wheat.

Some authors combine the Sphaeropsideae with the closely allied Melanconieae. M. C. Cooke contends that the Sphaeropsideae should be considered apart from the Melanconieae, on the fundamental basis that the former possess a distinct perithecium, while the latter do not.

The Sphaeropsideae as recently defined by Cooke are "Fungi possessed of a perithecium, but without asci, ... sporules or stylospores being produced internally at the apex of more or less distinct supporting hyphae or pedicels, termed sporophores."

The Sphaeropsideae somewhat resemble the Pyrenomyceteae in external characteristics, but differ from them in the absence of asci and paraphyses. Saccardo retains all the species in his Sylloge, but relegates them to an inferior position as imperfect fungi.

The group Pyrenomycetes, or Sphaeriacei, as at first recognized by Fries, included not only the Sphaeriacei and the Perisporacei, but also the Sphaeropsidei and Melanconiaceae. Later, when ascigerous fungi were separated from stylosporous fungi, this group was revised, the ascigerous species only being retained. As at present limited, the Pyrenomycetes are "ascigerous fungi having the fructification enclosed within a perithecium."

They constitute a very large group, the described species, according to Cooke's Census of Fungi, numbering not less than 10,500, or at least 1,000 more than all the recorded species of Hymenomycetes. The plants are microscopic in size, and grow upon vegetable or animal substances.

HYPHOMYCETES.

With regard to the Hyphomycetes, Cooke takes the ground that in their internal relations to each other, and their external relations to the remaining orders, the Hyphomycetes are undoubtedly a well-defined and natural group, and should have place as such in a systematic work. It is a large order, containing nearly 5,000 species, mostly parasitic on dead animals and vegetable matter. The spores, termed conidia, are free, as in Hymenomycetes. The species are microscopic in size, and the hyphae are strongly developed. They have no hymenium and no true basidia, and are non-sexual in their reproduction.

The four primary sections are the Mucedineae, or "white moulds;" the Dematieae, or "black moulds;" the Stilbea, with the hyphae or thread-like filaments pallid or brown, and densely cohering, and the Tubercularieae, with the hyphae densely compacted in wart-like pustules of somewhat gelatinous consistency.

The divisions called Melanconieae, Sphaeropsideae, and Hyphomyceteae are not recognized in the Brefield system of classification as distinct groups. Massee and Cooke, with other mycologists, take exception to this omission and its implication, in their discussion of the subject, giving consistent reasons for the retention of these groups in systematic works.

PHYCOMYCETES OR PHYSOMYCETES.

As originally defined by Berkeley, this group was composed chiefly of the old typical Mucors and their allies, and was then termed Physomycetes. In the newer system of classification its original definition has been extended so as to include a number of groups somewhat dissimilar in their habits and characteristics, but "united under the conservating bond of a dimorphic reproduction," and the name has been changed to Phycomycetes. As at present recognized "the Phycomycetes are characterized by a unicellular mycelium, often parasitic on plants or animals, sometimes saprophytic, developed in the air or in water. Reproduction sexual or asexual." As thus interpreted, Phycomycetes includes the Mucoracei; the Peronosporaceae, or "rotting moulds;" the Cystopi, or "white rusts;" the Saprolegniaceae, or "fish moulds;" the Entomophthoraceae, or "insect moulds," together with a few minor groups of doubtful natural affinity.

BIBLIOGRAPHY.

Saccardo, P. A. "Sylloge Sphaeropsidearum et Melanconiearum," in Sylloge Fungorum. Vol. iii. Imp. 8vo. Padua, 1884.

L. A. Crie. Recherches sur les Pyrenomycetes inferieurs du group de Depazees. 8vo. Paris, 1878.

J. C. Corda. Icones Fungorum. Fol. 6 vol. Prague, 1837-'54.