Button mushroom
Encyclopedia
Agaricus bisporus—known variously as the common mushroom, button mushroom, white mushroom, table mushroom, champignon mushroom, crimini mushroom, Swiss brown mushroom, Roman brown mushroom, Italian brown, Italian mushroom, cultivated mushroom, or when mature, the Portobello mushroom—is an edible
basidiomycete
mushroom
native to grassland
s in Europe
and North America
. Agaricus bisporus is cultivated
in more than 70 countries and is one of the most commonly and widely consumed mushrooms in the world.
history. It was first described by English botanist Mordecai Cubitt Cooke
in his 1871 Handbook of British Fungi, as a variety (var. hortensis) of Agaricus campestris
. Danish mycologist Jakob Emanuel Lange
later reviewed a cultivar
specimen, and dubbed it Psalliota hortensis var. bispora in 1926. In 1938, it was promoted to species
status and renamed Psalliota bispora. Emil Imbach imparted the species' current scientific name, Agaricus bisporus, after the genus Psalliota was renamed to Agaricus in 1946. The specific epithet bispora distinguishes the two-spored basidia from four-spored varieties.
Among English speakers, Agaricus bisporus is known by many names. A young specimen with a closed cap and either pale white or light brown flesh is known as a button mushroom or white mushroom. In strains with darker flesh, the immature mushroom is variously marketed as a crimini mushroom, baby portobello, baby bella, mini bella, portabellini, Roman mushroom, Italian mushroom, or brown mushroom. At this stage of maturation, the cap may also begin to open slightly. In maturity, it is called a portobello. The French name is champignon de Paris ("Paris mushroom").
The spellings "portobello", "portabella", and "portabello" are all used, but the first of these spellings is the most common.
or cap of the original wild species is a pale grey-brown in color, with broad, flat scales on a paler background and fading toward the margins. It is first hemispherical in shape before flattening out with maturity, and 5–10 cm (2–4 in) in diameter. The narrow, crowded gills are free and initially pink, then red-brown and finally a dark brown with a whitish edge from the cheilocystidia. The cylindrical stipe
is up to 6 cm (2⅓ in) tall by 1–2 cm wide and bears a thick and narrow ring
, which may be streaked on the upperside. The firm flesh is white though stains a pale pinkish-red on bruising. The spore print
is dark brown. The spores are oval to round and measure around 4.5–5.5 x 5–7.5 μm, and the basidia usually two-spored, although two tetrasporic varieties have been described from the Mojave desert
and the Mediterranean with predominantly heterothallic
and homothallic
lifestyles, respectively
Commonly found in fields and grassy areas after rain from late spring through to autumn worldwide, especially in association with manure
. It is widely collected and eaten, even by those who would not normally experiment with mushrooming.
(Amanita sp.), but the latter can be distinguished by their volva
or cup at the base of the mushroom and pure white gills (as opposed to pinkish or brown of Agaricus bisporus). Thus it is important to always clear away debris and examine the base of a mushroom, as well as cutting open young specimens to check the gills. Furthermore, the destroying angel grows in moss
y woods and lives symbiotically with spruce
.
A more common and less dangerous mistake is to confuse Agaricus bisporus with Agaricus xanthodermus
, an inedible mushroom found worldwide in grassy areas. Agaricus xanthodermus has an odor reminiscent of phenol
; its flesh turns yellow when bruised. This fungus causes nausea
and vomiting in some people.
The poisonous European species Entoloma sinuatum
has a passing resemblance but has yellowish gills turning pink and lacks a ring.
in 1707. French agriculturist Olivier de Serres
noted that transplanting mushroom mycelia would lead to 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 in beds of composted manure or inoculating 'bricks' of compressed litter, loam
and manure. Spawn collected this way contained pathogens and crops would be commonly infected or not grow at all.
In 1893, sterilized, or pure culture, spawn was discovered and produced by the Pasteur Institute
in Paris. Today's commercial variety of the common mushroom was originally a light brown color. In 1926, a Pennsylvania
n mushroom farmer found a clump of common mushrooms with white caps in his mushroom bed. Like white bread it was seen as a more attractive food item and was very popular. As was done with the navel orange and Red Delicious
apple, cultures were grown from the mutant individuals, and most of the cream-colored store mushrooms we see today are products of this chance natural mutation.
Agaricus bisporus is now cultivated in at least 70 countries around the world. Global production in the early 1990s was reported to be more than 1.5 billion kg, worth more than US$ 2 billion.
as ergocalciferol
(vitamin D2), since they also contain high amounts of ergosterol
, by brief exposure to UV light the ergocalciferol contents rise immensely..
, potassium
, and phosphorus
, conjugated linoleic acid
and antioxidant
s.
A clinical trial
is scheduled to take place at the City of Hope National Medical Center
due to earlier research indicating that the common mushroom can inhibit aromatase
, and therefore may be able to lower estrogen
levels in the human body, which might reduce breast cancer
susceptibility.
A 2009 case control study of more than 2000 women correlated a large decrease of breast cancer
incidence in women who consumed mushrooms. Women in the study who consumed fresh mushrooms daily were 64% less likely to develop breast cancer, while those that combined a mushroom diet with regular green tea consumption reduced their risk of breast cancer by nearly 90%.
The table mushroom has also been shown to possess possible immune system
enhancing properties. An in vitro study demonstrated the mushroom enhanced dendritic cell
function.
derivatives, including agaritine
and gyromitrin
. However, this research also noted when cooked, these compounds were reduced significantly.
Edible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
basidiomycete
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...
native to grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Agaricus bisporus is cultivated
Fungiculture
Fungiculture is the process of producing food, medicine, and other products by the cultivation of mushrooms and other fungi.The word is also commonly used to refer to the practice of cultivating fungi by leafcutter ants, termites, ambrosia beetles, and marsh periwinkles.- Introduction :Mushrooms...
in more than 70 countries and is one of the most commonly and widely consumed mushrooms in the world.
Taxonomy and naming
The common mushroom has a complicated taxonomicTaxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
history. It was first described by English botanist Mordecai Cubitt Cooke
Mordecai Cubitt Cooke
Mordecai Cubitt Cooke was an English botanist and mycologist.Cooke came from a mercantile family in Horning, Norfolk, and worked as an apprentice to a fabric merchant before becoming a clerk in a law firm, but his chief interest was in botany. He founded the Society of Amateur Botanists in 1862...
in his 1871 Handbook of British Fungi, as a variety (var. hortensis) of Agaricus campestris
Agaricus campestris
Agaricus campestris is commonly known as the field mushroom or, in North America, meadow mushroom. It is a widely eaten gilled mushroom closely related to the cultivated button mushroom Agaricus bisporus.-Taxonomy:...
. Danish mycologist Jakob Emanuel Lange
Jakob Emanuel Lange
Jakob Emanuel Lange , was a Danish mycologist who studied the systematics of gilled mushrooms.His most well-known work is Flora Agaricina Danica, a five-volume plate work on the Agaricales of Denmark....
later reviewed a cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
specimen, and dubbed it Psalliota hortensis var. bispora in 1926. In 1938, it was promoted to species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
status and renamed Psalliota bispora. Emil Imbach imparted the species' current scientific name, Agaricus bisporus, after the genus Psalliota was renamed to Agaricus in 1946. The specific epithet bispora distinguishes the two-spored basidia from four-spored varieties.
Among English speakers, Agaricus bisporus is known by many names. A young specimen with a closed cap and either pale white or light brown flesh is known as a button mushroom or white mushroom. In strains with darker flesh, the immature mushroom is variously marketed as a crimini mushroom, baby portobello, baby bella, mini bella, portabellini, Roman mushroom, Italian mushroom, or brown mushroom. At this stage of maturation, the cap may also begin to open slightly. In maturity, it is called a portobello. The French name is champignon de Paris ("Paris mushroom").
The spellings "portobello", "portabella", and "portabello" are all used, but the first of these spellings is the most common.
Description
The pileusPileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
or cap of the original wild species is a pale grey-brown in color, with broad, flat scales on a paler background and fading toward the margins. It is first hemispherical in shape before flattening out with maturity, and 5–10 cm (2–4 in) in diameter. The narrow, crowded gills are free and initially pink, then red-brown and finally a dark brown with a whitish edge from the cheilocystidia. The cylindrical stipe
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
is up to 6 cm (2⅓ in) tall by 1–2 cm wide and bears a thick and narrow ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...
, which may be streaked on the upperside. The firm flesh is white though stains a pale pinkish-red on bruising. The spore print
Spore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
is dark brown. The spores are oval to round and measure around 4.5–5.5 x 5–7.5 μm, and the basidia usually two-spored, although two tetrasporic varieties have been described from the Mojave desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
and the Mediterranean with predominantly heterothallic
Heterothallic
Heterothallic species have sexes that reside in different individuals....
and homothallic
Homothallic
Homothallic refers to the possession, within a single organism, of the resources to reproduce sexually.It can be contrasted to heterothallic.It is often used to categorize fungi. In yeast, heterothallic cells have mating types a and α...
lifestyles, respectively
Commonly found in fields and grassy areas after rain from late spring through to autumn worldwide, especially in association with manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...
. It is widely collected and eaten, even by those who would not normally experiment with mushrooming.
Similar species
The common mushroom could be confused with young specimens of the deadly poisonous destroying angelDestroying angel
The name destroying angel applies to several similar, closely related species of deadly all-white mushrooms in the genus Amanita. They are Amanita bisporigera and A. ocreata in eastern and western North America, and A. virosa in Europe. Another very similar species, A. verna or fool's mushroom was...
(Amanita sp.), but the latter can be distinguished by their volva
Volva (mycology)
The volva is a mycological term to describe a cup-like structure at the base of a mushroom that is a remnant of the universal veil. This macrofeature is important in wild mushroom identification due to it being an easily observed, taxonomically significant feature which frequently signifies a...
or cup at the base of the mushroom and pure white gills (as opposed to pinkish or brown of Agaricus bisporus). Thus it is important to always clear away debris and examine the base of a mushroom, as well as cutting open young specimens to check the gills. Furthermore, the destroying angel grows in moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
y woods and lives symbiotically with spruce
Spruce
A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
.
A more common and less dangerous mistake is to confuse Agaricus bisporus with Agaricus xanthodermus
Agaricus xanthodermus
Agaricus xanthodermus, commonly known as the yellow-staining mushroom, is a mushroom of thegenus Agaricus, which displays a strong yellow colouration at the base of the stem when cut...
, an inedible mushroom found worldwide in grassy areas. Agaricus xanthodermus has an odor reminiscent of phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
; its flesh turns yellow when bruised. This fungus causes nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
and vomiting in some people.
The poisonous European species Entoloma sinuatum
Entoloma sinuatum
Entoloma sinuatum is a poisonous mushroom found across Europe and North America. Some guidebooks refer to it by its older scientific names of Entoloma lividum or Rhodophyllus sinuatus...
has a passing resemblance but has yellowish gills turning pink and lacks a ring.
Cultivation
The earliest description of the commercial cultivation of Agaricus bisporus was made by French botanist Joseph Pitton de TournefortJoseph Pitton de Tournefort
Joseph Pitton de Tournefort was a French botanist, notable as the first to make a clear definition of the concept of genus for plants.- Biography :...
in 1707. French agriculturist Olivier de Serres
Olivier de Serres
Olivier de Serres was a French author and soil scientist whose Théâtre d'Agriculture was the text book of French agriculture in the 17th century..Serres was born at Villeneuve-de-Berg, Ardèche...
noted that transplanting mushroom mycelia would lead to 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 in beds of composted manure or inoculating 'bricks' of compressed litter, loam
Loam
Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...
and manure. Spawn collected this way contained pathogens and crops would be commonly infected or not grow at all.
In 1893, sterilized, or pure culture, spawn was discovered and produced by the Pasteur Institute
Pasteur Institute
The Pasteur Institute is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who made some of the greatest breakthroughs in modern medicine at the time, including pasteurization and vaccines for anthrax...
in Paris. Today's commercial variety of the common mushroom was originally a light brown color. In 1926, a Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
n mushroom farmer found a clump of common mushrooms with white caps in his mushroom bed. Like white bread it was seen as a more attractive food item and was very popular. As was done with the navel orange and Red Delicious
Red Delicious
The Red Delicious is a clone of apple cultigen, now comprising more than 50 cultivars, that was recognized in Madison County, Iowa, United States, in 1880...
apple, cultures were grown from the mutant individuals, and most of the cream-colored store mushrooms we see today are products of this chance natural mutation.
Agaricus bisporus is now cultivated in at least 70 countries around the world. Global production in the early 1990s was reported to be more than 1.5 billion kg, worth more than US$ 2 billion.
Vitamin D
While Agaricus bisporus only contains 40 IU of vitamin DVitamin D
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....
as ergocalciferol
Ergocalciferol
Ergocalciferol is a form of vitamin D, also called vitamin D2. It is marketed under various names including Deltalin , Drisdol and Calcidol...
(vitamin D2), since they also contain high amounts of ergosterol
Ergosterol
Ergosterol is a sterol found in fungi, and named for ergot, a common name for the members of the fungal genus Claviceps from which ergosterol was first isolated. Ergosterol does not occur in plant or animal cells...
, by brief exposure to UV light the ergocalciferol contents rise immensely..
Potential medicinal value
Agaricus bisporus also contains sodiumSodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, and phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
, conjugated linoleic acid
Conjugated linoleic acid
Conjugated linoleic acids are a family of at least 28 isomers of linoleic acid found mainly in the meat and dairy products derived from ruminants. As the name implies, the double bonds of CLAs are conjugated, with only one single bond between them....
and antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
s.
A clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
is scheduled to take place at the City of Hope National Medical Center
City of Hope National Medical Center
City of Hope National Medical Center, is a private, not-for-profit clinical research center, hospital and graduate medical school located in Duarte, California, United States...
due to earlier research indicating that the common mushroom can inhibit aromatase
Aromatase
Aromatase is an enzyme responsible for a key step in the biosynthesis of estrogens. It is a member of the cytochrome P450 superfamily , which are monooxygenases that catalyze many reactions involved in steroidogenesis. In particular, aromatase is responsible for the aromatization of androgens into...
, and therefore may be able to lower estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
levels in the human body, which might reduce breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
susceptibility.
A 2009 case control study of more than 2000 women correlated a large decrease of breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
incidence in women who consumed mushrooms. Women in the study who consumed fresh mushrooms daily were 64% less likely to develop breast cancer, while those that combined a mushroom diet with regular green tea consumption reduced their risk of breast cancer by nearly 90%.
The table mushroom has also been shown to possess possible immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
enhancing properties. An in vitro study demonstrated the mushroom enhanced dendritic cell
Dendritic cell
Dendritic cells are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system. That is, dendritic cells function as antigen-presenting cells...
function.
Health risks
Some studies have revealed that raw A. bisporus - along with some other edible mushrooms - contain small amounts of carcinogenic hydrazineHydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
derivatives, including agaritine
Agaritine
Agaritine is an aromatic, antiviral, hydrazine-derivative mycotoxin and IARC Group 3 carcinogen that occurs in mushroom species of the genus Agaricus.-Occurrence:...
and gyromitrin
Gyromitrin
Gyromitrin is a toxin and carcinogen present in several members of the fungal genus Gyromitra, most notably the false morel G. esculenta. It is unstable and is easily hydrolyzed to the toxic compound monomethylhydrazine, a component of some rocket fuels. Monomethylhydrazine acts on the central...
. However, this research also noted when cooked, these compounds were reduced significantly.
See also
- FungicultureFungicultureFungiculture is the process of producing food, medicine, and other products by the cultivation of mushrooms and other fungi.The word is also commonly used to refer to the practice of cultivating fungi by leafcutter ants, termites, ambrosia beetles, and marsh periwinkles.- Introduction :Mushrooms...
- List of Agaricus species
- Medicinal mushroomsMedicinal mushroomsMedicinal mushrooms are mushrooms, or mushroom extracts, that are used or studied as possible treatments for diseases. Lentinula edodes , Grifola frondosa , Ganoderma lucidum , and Cordyceps, have a history of medicinal use spanning millennia in parts of Asia...
- Effect of sunlight on mushrooms