Pleurotus ostreatus

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.

Fruiting body containing fibers (usually in the stalk)

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

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

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

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

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

Cap fleshy, firm to tough, fairly large (typically over 3" at maturity); sometimes white but often some shade of brown or grey
Flesh (especially gills) often yellowing as it dries out (see second picture)
Causes a white rot

Pleurotus ostreatus     (Jacquin: Fries) Kummer

Here are the characters that distinguish this species from the others in its group. For its more general characters, see higher up on the page.
If there's just a few words or a microscopic feature here, a more thorough description can be found above.

Diagnosis

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

• This shows them a little older, starting to dry up and turn yellow

• Sometimes the caps can be quite dark

• Spores 7-9 x 3-3.5 µm

Comments

I can only describe the odor (when fresh) as a sort of spicy brown sugar smell. It goes well with brown sugar: I have candied them in it


 

 

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