Fungus

Pleurotus

A genus of basidiomycetous fungi, family Pleurotaceae, order AGARICALES, that grows on logs or tree stumps in shelflike layers. The species P. ostreatus, the oyster mushroom, is a choice edible species and is the most frequently encountered member of the genus in eastern North America. (Alexopoulos et al., Introductory Mycology, 4th ed, p531)