''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 World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

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 Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...

(which is also characteristic of bitter almonds).

Name

Both the Latin and common names refer to the shape of the fruiting body. The Latin ''pleurotus'' (side-ear) refers to the sideways growth of the stem with respect to the cap, while the Latin ''ostreatus'' (and the English common name,

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

) 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''.

Description

The mushroom has a broad, fan or oyster-shaped cap spanning ; 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 A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

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 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

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 ''Omphalotus olivascens'', commonly known as the western jack-o'-lantern mushroom, is an orange to brown-colored gilled mushroom native to California and Mexico. Taxonomy The fungus was described as new to science in 1976 by American mycolog ...

'', the western jack-o'-lantern mushroom and ''

Clitocybe dealbata ''Clitocybe dealbata'', also known as the ivory funnel, is a small white funnel-shaped toadstool widely found in lawns, meadows and other grassy areas in Europe and North America. Also known as the sweating mushroom, it derives this name from t ...

'', the ivory funnel mushroom, both bear a resemblance to ''Pleurotus ostreatus''. Both ''Omphalotus olivascens'' and ''Clitocybe dealbata'' contain muscarine and are toxic.

Carnivorous activity

''Pleurotus ostreatus'' is a

carnivorous fungus Carnivorous fungi or predaceous fungi are fungi that derive some or most of their nutrients from trapping and eating microscopic or other minute animals. More than 200 species have been described, belonging to the phyla Ascomycota, Mucoromycotina, ...

, preying on

nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

by using a

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

-dependent toxin that paralyzes the prey within minutes of contact, causing

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated diges ...

and formation of a

slurry A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped on a device such as a centrifugal p ...

to facilitate ingestion as a protein-rich food source.

Habitat

The oyster mushroom is widespread in many temperate and subtropical forests throughout the world, although it is absent from the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Thou ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, being replaced by '' P. pulmonarius'' and '' P. populinus''. It is a

saprotroph Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ( ...

that acts as a primary decomposer of wood, especially deciduous trees, and beech trees in particular.Phillips, Roger (2006), Mushrooms. Pub. McMilan, . P. 266. It is a white-rot wood-decay fungus. The oyster mushroom is one of the few known carnivorous mushrooms. Its

mycelia Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates in ...

can kill and digest

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant- parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a bro ...

s, which is believed to be a way in which the mushroom obtains

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

. 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 Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense soli ...

Uses

Culinary

The oyster mushroom is a choice edible, and is a

delicacy A delicacy is usually a rare and expensive food item that is considered highly desirable, sophisticated, or peculiarly distinctive within a given culture. Irrespective of local preferences, such a label is typically pervasive throughout a r ...

in Japanese,

Korean Korean may refer to: People and culture * Koreans, ethnic group originating in the Korean Peninsula * Korean cuisine * Korean culture * Korean language **Korean alphabet, known as Hangul or Chosŏn'gŭl **Korean dialects and the Jeju language ** ...

and

Chinese cuisine Chinese cuisine encompasses the numerous cuisines originating from China, as well as overseas cuisines created by the Chinese diaspora. Because of the Chinese diaspora and historical power of the country, Chinese cuisine has influenced many o ...

. It is frequently served on its own, in soups, stuffed, or in

stir-fry Stir frying () is a cooking technique in which ingredients are fried in a small amount of very hot oil while being stirred or tossed in a wok. The technique originated in China and in recent centuries has spread into other parts of Asia and ...

recipes with

soy sauce Soy sauce (also called simply soy in American English and soya sauce in British English) is a liquid condiment of Chinese origin, traditionally made from a fermented paste of soybeans, roasted grain, brine, and ''Aspergillus oryzae'' or '' As ...

. Oyster mushrooms may be used in sauces, such as

oyster sauce Oyster sauce describes a number of sauces made by cooking oysters. The most common in modern use is a viscous dark brown condiment made from oyster extracts,The Times, 22 January 1981; ''Cook Accidentally on purpose'' sugar, salt and water thic ...

. The mushroom's taste has been described as mild with a slight odor similar to

anise Anise (; '), also called aniseed or rarely anix is a flowering plant in the family Apiaceae native to Eurasia. The flavor and aroma of its seeds have similarities with some other spices and herbs, such as star anise, fennel, licorice, and t ...

. 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. Some toxic '' Lentinellus'' species are similar in appearance, but have gills with jagged edges and finely haired caps.

Other uses

The pearl oyster mushroom is also used to create

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates ...

bricks, mycelium furniture, and leather-like products. 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. ''P. ostreatus'' is also capable of growing upon and degrading oxo-biodegradable plastic bags; it can also contribute to the degradation of green polyethylene.

Similar species

Similar species include ''

Pleurocybella porrigens ''Pleurocybella porrigens'' is a species of fungus in the family Phyllotopsidaceae. The species is widespread in temperate forests of the Northern Hemisphere. ''P. porrigens'', known as the angel wing, is a white-rot wood-decay fungus ...

'', '' Hohenbuehelia petaloides'', and the hairy-capped '' Phyllotopsis nidulans.''

References

External links

*
Video footage of ''Pleurotus ostreatus''

{{Authority control Pleurotaceae Fungi described in 1774 Fungi of Europe Fungi in cultivation Edible fungi Carnivorous fungi