The simple conidiophores vary in size, and in the number and shape of the conidia; they, however, resemble the basidia, and are doubtless an early stage in the development of the definitely formed basidia.
Finally, well-defined chlamydospores, formed in various ways, appear in the Basidiomycetes as supplementary reproductive bodies (compare p. [90]). Among the Protobasidiomycetes, chlamydospores are at present only found among the Uredinaceæ, but in various forms; in the majority of families of the Autobasidiomycetes oidia frequently occur (Fig. [162]), but genuine chlamydospores seldom.
In the same species several of the known forms of reproduction may be distinguished.
The mycelium is generally composed of white, branched strands, consisting of numerous felted hyphæ; in some, sclerotia are found.—The great majority are saprophytes; some (particularly all the Uredinaceæ), are parasites.
Divisions of the Basidiomycetes.
- Series 1. Protobasidiomycetes: partly gymnocarpic, partly angiocarpic.
- „ 2. Autobasidiomycetes.
- Family 1. Dacryomycetes: gymnocarpic.
- „ 2. Hymenomycetes: partly gymnocarpic, partly hemiangiocarpic.
- „ 3. Phalloideæ: hemiangiocarpic.
- „ 4. Gasteromycetes: angiocarpic.
- Appended. Basidiolichenes: Lichen-forming basidiomycetes.
Series I. Protobasidiomycetes.
To this series belong the lowest of the Basidiomycetes. The basidia appear in two principal forms (1 and 2 on page [144]) and are divided into four cells, either transversely or longitudinally, each division forming a sterigma which abstricts a basidiospore. The first three orders, Uredinaceæ, Auriculariaceæ, and Tremellaceæ have gymnocarpic fruit-bodies, while those of the Pilacraceæ, on the contrary, are angiocarpic.
Order 1. Uredinaceæ (Rusts). All the Rust-Fungi are parasites, their mycelium living in the interior of the stems and leaves of their hosts, causing red, brown, or black spots—hence their name—and malformations, sometimes of considerable size.
The Rust-Fungi are gymnocarpic and destitute of a hymenium; for these reasons they are regarded as the simplest order of the Basidiomycetes. They are entirely parasitic, and their filamentous, branched mycelium ramifies in the intercellular spaces of its host, and often protrudes haustoria into the cells. The mycelium is perennial should it enter a woody tissue; it may also hibernate in the rhizomes of perennial herbs and permeate the shoots springing from them, but in the majority of the Rust-Fungi the mycelium has a very limited growth. The chief means of reproduction of the Rust-Fungi are the chlamydospores, which in the more highly developed species occur in three forms, namely, the teleuto-, æcidio-, and uredo-spores. The spores, in the host, are formed immediately beneath its epidermis, which is ruptured on the ripening of the spores, with the production of “rust,” brown, red, or black spots. Those chlamydospores which produce basidia are termed teleutospores. The spore on germination produces a transversely divided basidium, “promycelium,” on which basidiospores, “sporidia,” generally four in number, are produced on lateral sterigmata. This basidio-fructification is gymnocarpic; the basidia neither form a hymenium nor a fruit-body (only Cronartium and Gymnosporangium have a slight indication of a basidio-fructification).