|gills on hymenium|
|cap is offset|
|hymenium is decurrent|
|stipe is bare|
|spore print is white|
|ecology is saprotrophic|
Pleurotus ostreatus, the oyster mushroom, oyster fungus, or hiratake, is a common edible mushroom. It was first cultivated in Germany as a subsistence measure during World War I and is now grown commercially around the world for food. It is related to the similarly cultivated king oyster mushroom. Oyster mushrooms can also be used industrially for mycoremediation purposes.
The oyster mushroom is one of the more commonly sought wild mushrooms, though it can also be cultivated on straw and other media. It has the bittersweet aroma of benzaldehyde (which is also characteristic of bitter almonds).
Both the Latin and common names refer to the shape of the fruiting body. The Latin pleurotus (sideways) refers to the sideways growth of the stem with respect to the cap, while the Latin ostreatus (and the English common name, oyster) refers to the shape of the cap which resembles the bivalve of the same name. The reference to oyster may also derive from the slippery texture of the mushroom. The name grey oyster mushroom may be used for P. ostreatus.
The mushroom has a broad, fan or oyster-shaped cap spanning 2–30 cm (3⁄4–11+3⁄4 in); natural specimens range from white to gray or tan to dark-brown; the margin is inrolled when young, and is smooth and often somewhat lobed or wavy. The flesh is white, firm, and varies in thickness due to stipe arrangement. The gills of the mushroom are white to cream, and descend on the stalk if present. If so, the stipe is off-center with a lateral attachment to wood. The spore print of the mushroom is white to lilac-gray, and best viewed on dark background. The mushroom's stipe is often absent. When present, it is short and thick.
Omphalotus nidiformis is a toxic lookalike found in Australia and Japan. In North America, Omphalotus olivascens, the western jack-o'-lantern mushroom and Clitocybe dealbata, the ivory funnel mushroom, both bear a resemblance to Pleurotus ostreatus. Both Omphalotus olivascens and Clitocybe dealbata contain muscarine and are toxic.
P. ostreatus is a carnivorous fungus, preying on nematodes by using a calcium-dependent toxin that paralyzes the prey within minutes of contact, causing necrosis and formation of a slurry to facilitate ingestion as a protein-rich food source.
The oyster mushroom is widespread in many temperate and subtropical forests throughout the world, although it is absent from the Pacific Northwest of North America, being replaced by P. pulmonarius and P. populinus. It is a saprotroph that acts as a primary decomposer of wood, especially deciduous trees, and beech trees in particular. It is a white-rot wood-decay fungus.
The standard oyster mushroom can grow in many places, but some other related species, such as the branched oyster mushroom, grow only on trees. They may be found all year round in the UK.
While this mushroom is often seen growing on dying hardwood trees, it only appears to be acting saprophytically, rather than parasitically. As the tree dies of other causes, P. ostreatus grows on the rapidly increasing mass of dead and dying wood. They actually benefit the forest by decomposing the dead wood, returning vital elements and minerals to the ecosystem in a form usable to other plants and organisms. Oyster mushrooms bioaccumulate lithium.
The oyster mushroom is a choice edible, and is a delicacy in Japanese, Korean and Chinese cuisine. It is frequently served on its own, in soups, stuffed, or in stir-fry recipes with soy sauce. Oyster mushrooms may be used in sauces, such as oyster sauce. The mushroom's taste has been described as mild with a slight odor similar to anise. Oyster mushrooms are used in the Czech and Slovak contemporary cuisine in soups and stews in a similar fashion to meat. The oyster mushroom is best when picked young; as the mushroom ages, the flesh becomes tough and the flavor becomes acrid and unpleasant.
Oyster mushrooms were used to treat soil that had been polluted with diesel oil. The mushroom was able to convert 95% of the oil into non-toxic compounds. 
- Kummer, P. (1871). Der Führer in die Pilzkunde (1st ed.).
- Alan Davidson, Tom Jaine (2014). "Oyster mushroom". In Jaine, Tom (ed.). Oyster mushroom; In: The Oxford Companion to Food (3rd Ed.). Oxford University Press. doi:10.1093/acref/9780199677337.001.0001. ISBN 9780199677337.CS1 maint: uses authors parameter (link)
- Eger, G., Eden, G. & Wissig, E. (1976). Pleurotus ostreatus – breeding potential of a new cultivated mushroom. Theoretical and Applied Genetics 47: 155–163.
- Beltran-Garcia, Miguel J.; Estarron-Espinosa, Mirna; Ogura, Tetsuya (1997). "Volatile Compounds Secreted by the Oyster Mushroom (Pleurotus ostreatus)and Their Antibacterial Activities". Journal of Agricultural and Food Chemistry. 45 (10): 4049. doi:10.1021/jf960876i.
- Hall, Ian R. (April 2010). "Growing mushrooms: the commercial reality" (PDF). Lifestyle Farmer: 42–45. Retrieved 26 January 2012.
- Miller Jr., Orson K.; Miller, Hope H. (2006). North American Mushrooms: A Field Guide to Edible and Inedible Fungi. Guilford, CN: FalconGuide. p. 142. ISBN 978-0-7627-3109-1.
- Lee, Ching-Han; Chang, Han-Wen; Yang, Ching-Ting; Wali, Niaz; Shie, Jiun-Jie; Hsueh, Yen-Ping (2020-03-02). "Sensory cilia as the Achilles heel of nematodes when attacked by carnivorous mushrooms". Proceedings of the National Academy of Sciences. 117 (11): 6014–6022. doi:10.1073/pnas.1918473117. ISSN 0027-8424. PMC 7084146. PMID 32123065.
- Trudell, S.; Ammirati, J. (2009). Mushrooms of the Pacific Northwest. Timber Press Field Guides. Portland, Oregon: Timber Press. p. 134. ISBN 978-0-88192-935-5.
- Phillips, Roger (2006), Mushrooms. Pub. McMilan, ISBN 0-330-44237-6. P. 266.
- de Assunção et al. 2012, pp. 1123–1127. sfn error: no target: CITEREFde_Assunçãoda_Luzda_SilvaVieira2012 (help)
- "Slovak oyster mushroom recipes". Ringier Axel Springer SK. Retrieved 2015-07-21.
- Davis, R. Michael; Sommer, Robert; Menge, John A. (2012). Field Guide to Mushrooms of Western North America. Berkeley: University of California Press. p. 30. ISBN 978-0-520-95360-4. OCLC 797915861.
- Rhodes, Christopher J. (January 2014). "Mycoremediation (bioremediation with fungi) – growing mushrooms to clean the earth". Chemical Speciation & Bioavailability. 26 (3): 196–198. doi:10.3184/095422914X14047407349335. ISSN 0954-2299. S2CID 97081821.
- Davis, R. Michael; Sommer, Robert; Menge, John A. (2012). Field Guide to Mushrooms of Western North America. Berkeley: University of California Press. pp. 132–133. ISBN 978-0-520-95360-4. OCLC 797915861.
- Lincoff, G.H. (1981). National Audubon Society Field Guide to North American Mushrooms. Knopf. ISBN 978-0-394-51992-0
- Spahr, D.L. (2009). Edible and Medicinal Mushrooms of New England and Eastern Canada. North Atlantic Books. ISBN 978-1-55643-795-3
|Wikimedia Commons has media related to Pleurotus ostreatus.|