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oyster mushroom

oyster mushroom (Pleurotus ostreatus)

Features and Behaviors

The body of a fungus (mycelium) is made up of strands called mycelia. The mycelium grows within the soil, a dead tree or other object and is rarely seen. The fruiting body that produces spores is generally present for only a short period of time but is the most familiar part of the fungus to most people. The oyster mushroom has a white, gray or gray-yellow cap which may be about 10 inches wide. This cap is fan-shaped or funnel-shaped. The cap may or may not have a stalk. If the stalk is present, it is very short, no more than about one-half inch in length. The stalk is either attached to one side of the cap or off-center and is usually curved.

The oyster mushroom may be found statewide in Illinois. It grows in stumps, logs and rotten wood. It may appear singly or in clusters. Unlike plants, fungi do not have roots, stems, leaves, flowers or seeds. The oyster mushroom must absorb nutrients and water from the objects it grows in. Spores are produced in spring and late fall. The spores provide a means of reproduction, dispersal and survival in poor conditions. Spore production occurs when conditions are favorable, generally with warm temperatures and ample moisture.

Illinois Range


​Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Pleurotaceae

Illinois Status: common, native