90 AGARICACEiE Pleurotus 



as gluten, or obsolete or nearly so. Hymenophore confluent and 

 homogeneous with the fleshy stem, when present. Pileus usually 

 excentric, compact, spongy to fleshy or membranous, sometimes 

 resupinate. Stem usually excentric, lateral, annulate, simple or 



Fig. 20. — A, section of Pleurotus dryinus Quel. One-third 

 natural size. B, young state, section, showing veil ; c, section 

 of P. applicatus Quel. X 2. 



none ; when present without cartilaginous bark ; when the larger- 

 stemmed species grow vertically on prostrate trunks, the stem is 

 sometimes central or nearly so. Gills sinuate, adnate or decurrent,. 

 in some of the Resupinate often starting from an excentric point. 

 Spores more or less elliptical, smooth. (Fig. 20.) 



The majority of the species grow on trunks, branches, twigs,, 

 moss, etc., a few are terrestrial; many are large, handsome and 

 polymorphic ; some are small and resupinate. They generally 

 appear late in the year, 421 and 422 commonly grow in the spring 

 and reappear year after year on the same habitat. All are harmless,, 

 and a few are considered by some to be edible. All become putrid 

 when old, and none are leathery or woody — in this they differ from 

 members of Lentinus, Pamis, Xerotus, Trogia, Schizophyllum and 

 Lenzites. Species 407 — 448 



a. Exeeutriece. Pileus laterally extended ; stem excentric. 



Veil forming an annulus to the stem and hanging as a ragged 

 fringe at the margin of the pileus. 407 — 409 



P#7 obsolete. Gills sinuate or obtusely adnate. 410 — 417 



Veil obsolete. Stem distinct, somewhat vertical. Gills deeply 

 decurrent. 418 — 420 



Veil obsolete. Pileus lateral, sessile or extended behind into 

 a short, oblique, stem-like base. Gills deeply decurrent. 



421—425 



b. Dimidiatce. Pileus definitely lateral, immarginate behind, not 



at first resupinate. 426 — 435 



