2.Oyster mushrooms belong to the genus Pleurotus (Quel.) Fr., and today at least 70 species have been identified. Pleurotus was first recommended as a tribe within the genus Agaricus by Fries (1821) but was proposed as a separate genus by Quelet (1886). Pleurotus ostreatus (Jacq: Fr.) Kummer, the oyster mushroom, is the most cultivated species among oyster mushrooms and the type species of the genus Pleurotus. To clearly distinguish the type species from other oyster mushrooms it is called P. ostreatus in this document. Mating compatibility studies have shown that P. columbinus, P. florida, P. salignus, and P. spodoleucus are synonyms or subspecies taxa for P. ostreatus.