Hymenomycetes

Hymenomycetes, an order of fungi (q.v.) belonging to the sub-class Basidiomycetes (q.v.), and including the mushroom (q.v.) and most of the other plants to which the name fungi is popularly applied. They have generally a loosely-branched filamentous mycelium or "spawn," in the soil or other nidus on which they may grow, such as the stem of a tree, but the mycelium may be compacted into a sclerotium or into elongated strap-like strands, known in Agaricus melleus as rhizommphs, which ramify under the bark of pine-trees. From the mycelium rises the compound sporophore or hymenophorc, which is generally apileusor umbrella-like body on a stalk or stipes. In some, the entire sporophore is at first enclosed in a membrane, the volva or veluni universale; in others, a membrane, the velum partialc, encloses the lower surface of the pileus, and on bursting is represented by atom ring or annulus round the stipes. In Amanita (q.v.) both membranes are present. Through the sporophores of some forms, especially of Lactarius, hyphen secreting an abundant milky, but generally acrid, juice extend. The hymenium, or spore-bearing surface, is generally on the under side of the pileus.

It is variously disposed, being smooth in the Auricularini, on radiating lamella or "gills" in the Agarics (q.v.), lining tubes or "pores" in the Polyporei, and covering dependent spine-like bodies in Hydnci. It is made up of rows of club-shaped cells, some of which, known as parapliyses, are barren, others, known as cystidia (though also barren), of relatively greater size, and others, the basidia, ending in the points known as sterigmata, mostly four on each basidium, from which the spores, hence called sterigmatospores or basidiospores, are formed and abstricted. The Hymenomycetes thus differ from the Gasteromycetes (q.v.) in having the hymenium exposed to the air (angiocarpous) before the spores are ripe. There are no known sexual organs in these plants. The order is represented in all quarters of the globe, and comprises nearly all the fungi which are of value as food. It is not represented in a fossil state, except in Pleistocene peat.