The recorded edible species of the spore section Dermini are found in Pholiota, Cortinarius, and Paxillus. The larger proportion of the Pholiotas grow upon tree stumps. They have a fugacious, persistent friable ring, and are liable to be confused with the Cortinarii, unless attention is paid to the spidery veil and the iron-rust tint of the spores of the latter. Only a few of the species are recorded as edible, but none are known to be poisonous. Cortinarius is a large genus. It contains a larger proportion of edible species than Pholiota, and none are recorded as poisonous. The cobweb-like veil which extends from stem to margin of cap in the young species, and the rust-colored spores which dust the gills as the species mature, distinguish the genus from all others.
A characteristic feature of Paxillus, and one which makes it easily distinguishable from others of the same group, is the ease with which the gills as a whole can be separated from the substance or fleshy portion of the cap. There is an exception to this in the species Paxillus involutus, recorded by Peck as edible.
POLYPOREI.
Hymenium lining the cavity of tubes or pores which are sometimes broken up into teeth or concentric plates.—Berkeley's Outlines.
The plants of this second primary group or order of the family Hymenomycetes exhibit a greater dissimilarity of form and texture than do those of the Agaricini. Some of its genera consist almost wholly of coriaceous or woody plants. A few contain fleshy ones. Some of the species have a distinct stem, while others are stemless. With regard to the receptacle in the plants of the genera Boletus, Strobilomyces, etc., it forms a perfect cap, like that of the common Agaric, a cushion of tubes taking the place of gills on the under surface of the cap, the hymenium in this case lining the inner surface of the tubes from which the spores drop when mature.
In some species, such as those of the genus Poria, the receptacle is reduced to a single thin fibrous stratum, adhering closely to the matrix and exposing a surface of crowded pores, and in others it consists of fibrous strata formed in concentric layers.
A number of groups, each of which was treated in the original Friesian classification as a single genus, have more recently been recognized as comprising several distinct genera. In the Saccardian system the genera Trametes, Dædalea, Merulius, Porothelium, and Fistulina still retain the generic rank assigned to them by Fries, but the old genus Boletus is subdivided into four genera, Boletus, Strobilomyces, Boletinus, and Gyrodon, while Polyporus, originally a very large genus, is subdivided into the genera Polyporus, Fomes, Polystictus, and Poria. This arrangement was in part suggested by Fries in his later works, and is accepted by M. C. Cooke, as indicated in his latest work on fungi.
Quoting M. C. Cooke, "Strobilomyces is Boletus with a rough warty and scaly pileus; Boletinus is Boletus with short, large radiating pores; and Gyrodon is Boletus with elongated sinuate irregular pores, all fleshy, firm fungi of robust habit, possessing stem and cap." The species of the genus Polyporus as now restricted are somewhat fleshy in the young stage, shrinking as they mature and dry, and becoming indurated with age. In Fomes the species, of woody consistency from the first, have no room for shrinkage, and are quite rigid; the tubes being in strata, and the strata growing yearly, the species are virtually perennial. The pileus of the plant shows a rigid polished crust resulting from resinous exudations.
In Polystictus the plants are usually small, thin, tough, and irregular in outline, the tubes exceedingly short, with thin walls, which easily split up, giving the pores at times a toothed or fringed appearance. The surface is velvety, or hairy, and zoned in varying colors. They are very common upon decaying tree stumps, often covering the surface of the stump in gaily colored layers. Not esculent.