Oyster Mushroom

Pleurotus ostreatus and P. pulmonarius


Photo of oyster mushrooms growing on a tree trunk
Oyster mushrooms grow in overlapping clusters on logs, stumps, and trees.
Jon Rapp



Gilled, in shelflike clusters; broad, fleshy, whitish, grayish, or tan cap; stubby, off-center stalk. Grows on stumps, logs, and trunks of deciduous trees. Year-round. Cap shell-shaped, semicircular to elongated; margin is smooth, sometimes wavy; whitish to grayish to tan; texture velvety; flesh is thick, white. Gills narrow; spacing nearly distant; white, becoming yellowish; attachment descending the stalk. Stalk (if present) short, thick; white; base is hairy; off-center, solid. Spore print white to grayish-lilac. Spores magnified are narrowly elliptical, smooth, colorless.

There are no lookalikes in Missouri that are poisonous.


Cap width: 1–6 inches; stalk length: to 1¼ inches; stalk width: to ¾ inch.

Habitat and conservation

Grows in clusters on stumps, logs, and trunks of deciduous trees. P. ostreatus fruits year-round, especially after a good rain, if the weather is mild. P. pulmonarius fruits only during warm months. It is occasionally covered with a bright yellow slime mold. Oyster mushrooms sometimes appear to "smoke" from the mass release of spores. A single "oyster log" can refruit several times a season.

image of Oyster Mushroom distribution map
Distribution in Missouri



Considered a choice edible, wild oyster mushrooms have a much better flavor than the cultivated oyster mushrooms found at most grocery stores. That said, easy-to-use kits for growing oyster mushrooms at home are available, and these are educational, fun, and provide healthful food for the table.

Life cycle

The mycelium (network of fungal cells) of oyster mushrooms actually kills and eats some kinds of nematodes, plant parasites that damage plant roots. The nematodes provide the fungus with nitrogen, a nutrient that is otherwise difficult to break down in wood. The nematode-trapping ability is being studied as a possible biocontrol to prevent plant diseases caused by certain nematodes.

Human connections

This prized culinary mushroom has many proven health benefits.

It is also being explored as a "digester" of inorganic waste and as an environmentally responsible substitute for Styrofoam. The mycelium is grown in molds filled with waste grain, then heat-treated to stop growth when the mold is full.

People have found they can grow these choice edible mushrooms on coffee grounds and spent grain from beermaking.

Ecosystem connections

This is one of the many fungus species that live on decaying wood. It and other such saprobic fungi play an incredibly important role in breaking down the tough materials wood is made of and returning those nutrients to the soil.

An orange-and-black pleasing fungus beetle, Triplax thoracica, is often found on oyster mushrooms.