Pleurotus     Genus

Cortinarius husseyiKey to Gilled Mushrooms     Key
This is a key to gilled mushrooms, that is, mushrooms having a definite cap with a fertile surface consisting of gills. The fruiting body usually also has a stem, although that may be lateral or absent (usually, then, the mushroom is growing from wood). You can use this key to identify mushrooms that you find.

TricholomaAgaricales     Order
Fruiting body containing fibers (usually in the stalk)

Amanita onustaWhite Spored     Suborder
Spore print "light-colored": white or buff, sometimes tinged with pink or tan. Greenish and (except for the Russulales) yellow spore prints also go here
Stalk fibrous, not fracturing like a piece of chalk

TricholomataceaeTricholomataceae     Family
None of the special features distinguishing the other white-spored genera:
Gills not free, as in the Lepiotas and Amanitas
Basidia not extra-long, as in the Hygrophoraceae
Spores smooth, except for Lentinellus

HygrocybeLignicolous Trich     Subfamily
Growing on trees or dead wood, leaves, or sticks, or organic debris, often in moss

Pleurotus ostreatusTough LignoTrich     Tribe
Assume a lateral stem, unless otherwise noted in the diagnoses below
If laterally stemmed, then gills strongly decurrent

Pleurotus ostreatusOyster LignoTrich     Subtribe
Cap always smooth (perhaps thinly, minutely furry), never scaly or thickly or coarsely hairy
Gills white to buff, though perhaps discoloring yellow (along with cap) in age, unless covered by a veil
Growing on wood

Pleurotus     Genus     (Fries) Kummer

Pleurotus ostreatus


Pleurotus ostreatus

Narrow down your identification:

Pleurotus dryinusPleurotus dryinus
Cap 2-8" across; white, with greyish fibrils; margin and stalk (at the point where the gills end) hung with fragments of partial veil
Stalk over an inch thick in larger specimens, much thicker (in proportion to the rest of the fruiting body) than in Pleurotus ostreatus or Pleurotus porrigens

Pleurotus ostreatusPleurotus ostreatus
Cap generally 2-8" (I have found them LP-sized) across; white to brown, thick and fleshy
Almost always on hardwoods