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).