Agaricus bisporus

Agaricus bisporus, commonly known as thecultivated mushroom, is abasidiomycetemushroom native tograsslandsinEurasiaandNorth America. It iscultivatedin more than 70 countries and is one of the most commonly and widelyconsumed mushroomsin the world. It has two color states while immature – white and brown – both of which have various names, with additional names for the mature state, such aschestnut,portobello,portabellini,buttonandchampignon de Paris.
A. bisporushas some deadlypoisonouslookalikes in the wild, such asEntoloma sinuatum.
Thepileusor cap of the original wild species is a pale grey-brown, with broad, flat scales on a paler background and fading toward the margins. It is first hemispherical before flattening out with maturity, and measures
5–10 centimetres (2–4 inches) in diameter. The narrow, crowdedgillsare free and initially pink, then red-brown, and finally a dark brown with a whitish edge from thecheilocystidia. The cylindricalstipeis up to6 cm (2+1⁄2in) tall by1–2 cm (1⁄2–3⁄4in) wide and bears a thick and narrowring, which may be streaked on the upper side. The firm flesh is white, although it stains a pale pinkish-red on bruising.Thespore printis dark brown. The spores are oval to round and measure approximately 4.5–5.5 μm × 5–7.5 μm, and thebasidiausually two-spored, although two four-spored varieties have been described from theMojave Desertand theMediterranean, with predominantlyheterothallicandhomothalliclifestyles, respectively.
The common mushroom could be confused with young specimens of a group oflethal mushroomsin theAmanitagenus referred to asdestroying angels, but the latter may be distinguished by theirvolvaor cup at the base of the mushroom and pure white gills (as opposed to pinkish or brown ofA. bisporus).
A more common and less dangerous mistake is to confuseAgaricus bisporuswithA. xanthodermus, an inedible mushroom found worldwide in grassy areas.A. xanthodermushas an odor reminiscent ofphenol; its flesh turns yellow when bruised. This fungus causesnauseaand vomiting in some people.
The poisonous European speciesEntoloma sinuatumhas a passing resemblance but has yellowish gills, turning pink, and lacks a ring.
The common mushroom has a complicatedtaxonomichistory. It was first described by English botanistMordecai Cubitt Cookein his 1871Handbook of British Fungi, as avariety(var.hortensis) ofAgaricus campestris.DanishmycologistJakob Emanuel Langelater reviewed acultivarspecimen, and dubbed itPsalliota hortensisvar.bisporain 1926.In 1938, it was promoted tospeciesstatus and renamedPsalliota bispora.Emil Imbach (1897–1970) imparted the current scientific name of the species,Agaricus bisporusafter the genusPsalliotawas renamed toAgaricusin 1946.Thespecific epithetbisporadistinguishes the two-spored basidia from four-sporedvarieties.
When immature andwhite, this mushroom may be known as:
When immature andbrown, it may be known variously as:
When marketed in its mature state, the mushroom is brown with a cap measuring 10–15 cm (4–6 in).This form is commonly sold under the names portobello,portabella,or portobella. The etymology is disputed.
This mushroom is commonly found worldwide in fields and grassy areas following rain, from late spring to autumn, especially in association withmanure.
In 2022, world production of mushrooms (includingtruffles) was 48 million tonnes, led by China with 94% of the total (table). Japan and the United States were secondary producers.
The earliest scientific description of the commercial cultivation ofA. bisporuswas made by French botanistJoseph Pitton de Tournefortin 1707.French agriculturistOlivier de Serresnoted that transplanting mushroommyceliawould lead to the propagation of more mushrooms.
Originally, cultivation was unreliable as mushroom growers would watch for good flushes of mushrooms in fields before digging up the mycelium and replanting them in beds of composted manure or inoculating 'bricks' of compressed litter,loam, and manure. Spawn collected this way contained pathogens, and crops would be infected or not grow.In 1893, sterilized, or pure culture, spawn was discovered and produced by thePasteur Institutein Paris for cultivation on composted horse manure.
Modern commercial varieties of the common agaricus mushroom were originally light brown. The white mushroom was discovered in 1925 growing among a bed of brown mushrooms at the Keystone Mushroom Farm inCoatesville, Pennsylvania. Louis Ferdinand Lambert, the farm's owner and a mycologist by training, brought the white mushroom back to his laboratory. As with the reception of white bread, it was seen as a more attractive food item and became grown and distributed.Similar to the commercial development history of thenavel orangeandRed Deliciousapple, cultures were grown from the mutant individuals. Most cream-colored store mushrooms marketed today are products of this 1925 chance natural mutation.
A. bisporusis cultivated in at least seventy countries worldwide.
A. bisporusmushrooms are 92% water, 3%carbohydrates, 3%protein, and contain negligiblefat(table).
In a reference amount of 100 g (3.5 oz), raw white mushrooms provide 93 kilojoules (22 kilocalories) offood energyand are an excellent source (20% or more of theDaily Value, DV) of theB vitaminsriboflavin,niacin, andpantothenic acid(table). Fresh mushrooms are also a good source (10–19% DV) of thedietary mineralsphosphorusandpotassium(table).
While freshA. bisporusonly contains 0.2 micrograms (8 IU) ofvitamin Dper 100 g, theergocalciferol(D2) content increases substantially to 11.2 micrograms (446 IU)after exposure toUV light.