E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include whitish or grayish, dry cap with soft fibrils or scales; a fleeting veil on the margin and stem when young; decurrent, close, whitish gills that form grooves on stem; off-center, whitish, dry stem; and growth on living hardwoods. The description is derived from Arora(1) except where noted. Pleurotus dryinus is fairly common.

It is found throughout most of northern North America (Phillips) as well as in Europe. It has been reported from WA (Murrill) and CA (Lincoff(2)). There are collections from BC at the Pacific Forestry Centre and the University of British Columbia, and collections from OR at Oregon State University.

Cap:
4-20cm, convex sometimes becoming flat or slightly depressed when old, margin at first inrolled; "with soft grayish fibrils or scales, but sometimes whitish or in age yellowish"; dry, (Arora), fan-shaped to elongately ear-shaped, (Lincoff(2)), roundish but irregular, often humped, (Brown)

Flesh:
very thick, firm; white

Gills:
decurrent, fairly close, often veined or forking on the stem; white but sometimes discoloring yellowish when old, (Arora), narrow, with subgills; edges may be serrate, (Schalkwijk-Barendsen)

Stem:
3-10cm x 1-3cm, often short, equal or narrowing downward, "usually off-center but sometimes central", rather tough, solid; whitish, (Arora), usually horizontal, whitish, but becoming yellowish when bruised or with age, (Brown)

Veil:
membranous, white to grayish, forming a slight ring on stem "or leaving remnants on cap margin or disappearing entirely", (Arora)

Odor:
mild to pungent or fragrant (Arora), pleasant (Phillips), slightly fragrant (anise-like) to musty (Siegel)

Taste:
pleasant (Phillips), bitter almonds according to Kauffman (Brown)

Microscopic spores:
spores 9-12(17) x 3.5-5 microns, elliptic, smooth, inamyloid, (Arora), basidiospores 9.8-13.9 x 3.8-4.2 microns, cylindric to cylindric-elliptic, smooth, iodine-negative, colorless, with droplets, asexual aleuriospores 15-25 x 15-20 microns, nearly round, light yellow to light brown, with droplets; basidia 4-spored, 35-100 x 6-8 microns, narrowly clavate, with basal clamp connection; pleurocystidia and cheilocystidia not seen; clamps mentioned for cap cuticle and basidia, (Breitenbach)

Spore deposit:
white