Summary: Pleurocybella porrigens is distinguished by smooth, pliant, white caps with a shelf-like habit on conifer wood, and narrow, crowded, white or yellowish gills. The description is derived from Arora(1) except where noted. It is common in the Pacific Northwest.
Cap: 4-8(10)cm wide, projecting 2-5cm, fan-shaped to tongue-shaped or petal-shaped, margin at first incurved, often lobed or wavy when older; pure white to milky white, but sometimes creamy when old; smooth, not viscid
Flesh: very thin, pliant; white
Gills: decurrent if stem present, crowded, thin, narrow; white or yellowish
Stem: "absent or present only as a narrowed, stubby white base"
Veil: absent
Odor: mild (Arora), pleasant (Phillips)
Taste: mild (Arora), pleasant (Phillips)
Microscopic spores: spores 6-7 x 5-6 microns, nearly round, smooth, inamyloid, (Arora), spores 5.1-7.3 x 4.5-6.7 microns, nearly round, smooth, iodine negative, colorless, with droplets; basidia 4-spored, 30-36 x 5.5-7.5 microns, cylindric-clavate, with basal clamp; pleurocystidia and cheilocystidia not seen; clamps mentioned for cap cuticle and basidia, (Breitenbach)
Spore deposit: white (Arora), whitish (Breitenbach)
Notes: There are collections at the University of British Colombia from BC and at the University of Washington from WA, OR, and AK. It has been reported from ID by Andrew Parker, pers. comm., from CA by Arora, and is also found elsewhere in North America. Breitenbach(3) give the distribution as North America, Europe, and Asia.
EDIBILITY
In the past Pleurocybella porrigens was generally considered edible, but in 2004 there were 17 deaths in Japan: most or all deaths occurred in people who had kidney disorders and the average age was 70: they died of an acute brain condition; another person on kidney dialysis died in 2009 from this species, (Beug(1) and M. Beug pers. comm.).
Habitat and Range
SIMILAR SPECIES
Pleurotus ostreatus group is fleshier and grows mostly on deciduous wood, and is whitish to grayish to brownish. Ossicaulis lignatilis has a more prominent stem (less tongue-shaped), has grayish colors at some stages, prefers hardwoods, may have a farinaceous odor, and has elliptic to broadly elliptic spores (as opposed to nearly round). Panellus mitis has gelatinous cap skin and small cylindric spores.
Habitat
in shelving groups or overlapping clusters on old rotting conifers, especially hemlock; fruiting especially in fall