Agaricus Aurantioviolaceus
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''Agaricus'' is a
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
mushroom A mushroom or toadstool is the fleshy, spore-bearing Sporocarp (fungi), fruiting body of a fungus, typically produced above ground on soil or another food source. ''Toadstool'' generally refers to a poisonous mushroom. The standard for the n ...
-forming
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
containing both
edible An edible item is any item that is safe for humans to eat. "Edible" is differentiated from " eatable" because it does not indicate how an item tastes, only whether it is fit to be eaten. Nonpoisonous items found in nature – such as some mushroo ...
and
poisonous A poison is any chemical substance that is harmful or lethal to living organisms. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figurati ...
species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom ('' A. bisporus'') and the field mushroom ('' A. campestris''), the dominant
cultivated mushroom Fungiculture is the cultivation of fungi such as mushrooms. Cultivating fungi can yield foods (which include mostly mushrooms), medicine, construction materials and other products. A ''mushroom farm'' is involved in the business of growing fun ...
s of the West.


Taxonomy

Several origins of genus name ''Agaricus'' have been proposed. It possibly originates from ancient Sarmatia Europaea, where people Agari, promontory Agarum and a river Agarus were known (all located on the northern shore of
Sea of Azov The Sea of Azov is an inland Continental shelf#Shelf seas, shelf sea in Eastern Europe connected to the Black Sea by the narrow (about ) Strait of Kerch, and sometimes regarded as a northern extension of the Black Sea. The sea is bounded by Ru ...
, probably, near modern
Berdiansk Berdiansk or Berdyansk (, ; , ) is a port city in Zaporizhzhia Oblast, south-eastern Ukraine. It is on the northern coast of the Sea of Azov, which is connected to the Black Sea. It serves as the administrative center of Berdiansk Raion. The c ...
in Ukraine). Note also Greek , agarikón, "a sort of tree fungus" (There has been an ''Agaricon'' Adans. genus, treated by Donk in ''Persoonia'' 1:180.) For many years, members of the genus ''Agaricus'' were given the generic name ''Psalliota'', and this can still be seen in older books on mushrooms. All proposals to conserve ''Agaricus'' against ''Psalliota'' or vice versa have so far been considered superfluous. Dok reports
Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
' name is devalidated (so the proper author citation apparently is "L. ''per'' Fr., 1821") because ''Agaricus'' was not linked to Tournefort's name. Linnaeus places both ''Agaricus'' Dill. and ''Amanita'' Dill. in synonymy, but truly a replacement for ''Amanita'' Dill., which would require ''A. quercinus'', not ''A. campestris'' be the type. This question is compounded because
Elias Magnus Fries Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist. He is sometimes called the Mycology, "Linnaeus of Mycology". In his works he described and assigned botanical names to hundreds of fungus and li ...
himself used ''Agaricus'' roughly in Linnaeus' sense (which leads to issues with ''Amanita''), and ''A. campestris'' was eventually excluded from ''Agaricus'' by Karsten and was apparently in ''Lepiota'' at the time Donk wrote this, commenting that a type conservation might become necessary. The alternate name for the genus, ''Psalliota'', derived from the
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
''psalion''/ψάλιον, "ring", was first published by Fries (1821) as trib. ''Psalliota''. The type is ''
Agaricus campestris ''Agaricus campestris'' is a widely eaten gilled mushroom closely related to the cultivated '' A. bisporus'' (button mushroom). ''A. campestris'' is commonly known as the field mushroom or, in North America, meadow mushroom. It is ...
'' (widely accepted, except by Earle, who proposed ''A. cretaceus'').
Paul Kummer Paul Kummer (22 August 1834 – 6 December 1912) was a Minister (Christianity), minister, teacher, and scientist in Zerbst, Germany, known chiefly for his contribution to mycological botanical nomenclature, nomenclature. Earlier Taxonomy (biology), ...
(not Quélet, who merely excluded Stropharia) was the first to elevate the tribe to a genus. ''Psalliota'' was the tribe containing the type of ''Agaricus'', so when separated, it should have caused the rest of the genus to be renamed, but this is not what happened.


Phylogeny

The use of
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis to determine evolutionary relationships amongst ''Agaricus'' species has increased the understanding of this taxonomically difficult genus, although much work remains to be done to fully delineate infrageneric relationships. Prior to these analyses, the genus ''Agaricus'', as circumscribed by
Rolf Singer Rolf Singer (June 23, 1906 – January 18, 1994) was a German mycologist and Taxonomy (biology), taxonomist of gilled mushrooms (agarics). He wrote the book "The Agaricales in Modern Taxonomy (biology), Taxonomy". He fled to various countries d ...
, was divided into 42 species grouped into five sections based on reactions of mushroom tissue to air or various chemical reagents, as well as subtle differences in mushroom morphology.
Restriction fragment length polymorphism In molecular biology, restriction fragment length polymorphism (RFLP) is a technique that exploits variations in homologous DNA sequences, known as polymorphisms, populations, or species or to pinpoint the locations of genes within a sequence. T ...
analysis demonstrated this classification scheme needed revision.


Subdivisions

As of 2018, this genus is divided into 6
subgenera In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...
and more than 20
sections Section, Sectioning, or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sig ...
: Bon, Marcel (1987) ''The Mushrooms and Toadstools of Britain and North Western Europe''. Hodder and Stoughton, (paperback) (hardback) Subgenus ''
Agaricus ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom ...
'' * Section ''Agaricus'' :This is the group around the
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
of the genus, the popular edible '' A. campestris'' which is common across the
Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...
temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...
, and has been introduced to some other regions. One of the more ancient lineages of the genus, it contains species typically found in open grassland such as '' A. cupreobrunneus'', and it also includes at least one undescribed species. Their cap surface is whitish to pale reddish-brown and smooth to slightly fibrous, the flesh usually without characteristic smell, fairly soft, whitish, and remaining so after injury, application of KOH, or Schäffer's test (
aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...
and HNO3). '' A. annae'' may also belong here, as might '' A. porphyrocephalus'', but the flesh of the latter blushes red when bruised or cut, and it has an unpleasant smell of rotten fish when old; these traits are generally associated with subgenus ''Pseudochitonia'', in particular section ''Chitonioides''. The '' A. bresadolanus/ radicatus/ romagnesii'' group which may be one or several species is sometimes placed here, but may be quite distinct and belong to subgenus ''Spissicaules''. Subgenus '' Flavoagaricus'' * Section ''Arvense'' Konrad & Maubl. (sometimes named ''Arvensis'') :Traditionally contained about 20 rather large species similar to the horse mushroom '' A. arvensis'' in six subgroups. Today, several additional species are recognized – in particular in the ''A. arvensis''
species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
and placed here, such as '' A. aestivalis'', '' A. augustus'', '' A. caroli'', '' A. chionodermus'', '' A. deserticola'' (formerly ''Longula texensis''), '' A. fissuratus'', '' A. inapertus'' (formerly ''
Endoptychum ''Endoptychum'' is a genus of secotioid fungi in the family Agaricaceae. Like the majority of secotioid taxa, the individual species of ''Endoptychum'' are thought to be recent mutations from agaricoid species, hence, ''Endoptychum'' is likely ...
depressum''), '' A. macrocarpus'', '' A. nivescens'', '' A. osecanus'', '' A. silvicola'' and the doubtfully distinct '' A. essettei'', '' A. urinascens'', and the disputed
taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
'' A. abruptibulbus'', '' A. albertii'', '' A. altipes'', '' A. albolutescens'', '' A. brunneolus'', '' A. excellens'' and '' A. macrosporus''. It also includes '' A. subrufescens'' which started to be widely grown and traded under various obsolete and newly-invented names in the early 21st century, as well as the
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
n '' A. blazei'' with which the
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
ian ''A. subrufescens'' was often confused in the past. They have versatile
heterothallic Heterothallic species have sexes that reside in different individuals. The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable ...
life cycles, are found in a variety of often rather
arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...
habitats, and typically have a smooth white to scaly light brown cap. The flesh, when bruised, usually turns distinctly yellow to pinkish in particular on the cap, while the end of the stalk may remain white; a marked yellow stain is caused by applying KOH. Their sweetish smell of almond extract or
marzipan Marzipan is a confectionery, confection consisting primarily of sugar and almond meal (ground almonds), sometimes augmented with almond oil or extract. It is often made into Confectionery, sweets; common uses are chocolate-covered marzipan and ...
due to
benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond-li ...
and derived compounds distinguishes them from the section ''Xanthodermatei'', as does a bright dark-orange to brownish-red coloration in Schäffer's test. Many members of this subgenus are highly regarded as food, and even medically beneficial, but at least some are known to accumulate
cadmium Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like z ...
and other highly toxic chemicals from the environment, and may not always be safe to eat. Subgenus '' Minores'' :A group of buff-white to reddish-brown species. Often delicate and slender, the typical members of this subgenus do not resemble the larger ''Agaricus'' species at a casual glance, but have the same telltale chocolate-brown gills at spore maturity. Their flesh has a barely noticeable to pronounced sweetish smell, typically
almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...
-like, turns yellowish to brownish-red when cut or bruised at least in the lower stalk, yellow to orange with KOH, and orange to red in Schäffer's test. Species such as '' A. aridicola'' (formerly known as ''
Gyrophragmium ''Gyrophragmium'' is a genus of fungi in the family Agaricaceae. The genus was circumscribed by French botanist Camille Montagne in 1843. The species known as ''G. dunalii'' was determined to properly belong into genus ''Agaricus'', and since ' ...
dunalii''), '' A. colpeteii'', '' A. columellatus'' (formerly ''Araneosa columellata''), '' A. diminutivus'', '' A. dulcidulus'', '' A. lamelliperditus'', '' A. luteomaculatus'', '' A. porphyrizon'', '' A. semotus'' and '' A. xantholepis'' are included here, but delimitation to and indeed distinctness from subgenus ''Flavoagaricus'' is a long-standing controversy. Unlike these however, subgenus ''Minores'' contains no choice edible species, and may even include some slightly poisonous ones; most are simply too small to make collecting them for food worthwhile, and their edibility is unknown. * Section '' Leucocarpi'' :Includes '' A. leucocarpus''. * Section '' Minores'' :Includes '' A. comtulus'' and '' A. huijsmanii''. * Section '' Pantropicales'' :Includes '' A. candidolutescens'' and an undescribed relative. Subgenus '' Minoriopsis'' :Somewhat reminiscent of subgenus ''Minores'' and like it closely related to subgenus ''Flavoagaricus'', it contains species such as '' A. martinicensis'' and '' A. rufoaurantiacus''. Subgenus '' Pseudochitonia'' :This highly diverse clade of mid-sized to largish species makes up much the bulk of the genus' extant diversity, and this subgenus contains numerous as of yet undescribed species. It includes both the most prized edible as well as the most notoriously poisonous ''Agaricus'', and some of its sections are in overall appearance more similar to the more distantly related ''Agaricus'' proper and ''Flavoagaricus'' than to their own closest relatives. Some species in this subgenus, such as '' A. goossensiae'' and '' A. rodmanii'', are not yet robustly assigned to one of the sections. * Section '' Bohusia'' :Includes '' A. bohusii'' which resembles one of the dark-capped ''Flavoagaricus'' or ''Xanthodermatei'' but does not stain yellow with the standard (10%) KOH testing solution. It is a woodland species, edible when young, but when mature and easily distinguished from similar species it may be slightly poisonous. Other members of this section include '' A. crassisquamosus'', '' A. haematinus'', and '' A. pseudolangei''. * Section '' Brunneopicti'' :A section notable for containing a considerable number of undescribed species in addition to '' A. bingensis'', '' A. brunneopictus'', '' A. brunneosquamulosus'', '' A. chiangmaiensis'', '' A. duplocingulatus'', '' A. megacystidiatus'', '' A. niveogranulatus'', '' A. sordidocarpus'', '' A. subsaharianus'', and '' A. toluenolens''. * Section '' Chitonioides'' :Contains species such as '' A. bernardii'' and the doubtfully distinct '' A. bernardiiformis'', '' A. gennadii'', '' A. nevoi'', '' A. pequinii'', '' A. pilosporus'' and '' A. rollanii'', which strongly resemble the members of section ''Duploannulatae'' and are as widely distributed. However, their flesh tends to discolor more strongly red when bruised or cut, with the discoloration slowly getting stronger. Their smell is usually also more pronounced
umami Umami ( from ), or savoriness, is one of the five basic tastes. It is characteristic of broths and cooked meats. People taste umami through taste receptors that typically respond to glutamates and nucleotides, which are widely present in me ...
-like, in some even intensely so. Some are edible and indeed considered especially well-tasting, while the unusual '' A. maleolens'' which may also belong here has an overpowering aroma which renders it inedible except perhaps in small amounts as a vegan
fish sauce Fish sauce is a liquid condiment made from fish or krill that have been coated in salt and fermented for up to two years. It is used as a staple seasoning in East Asian cuisine and Southeast Asian cuisine, particularly Myanmar, Cambodia, L ...
substitute. * Section '' Crassispori'' :Related to section ''Xanthodermatei'' as traditionally circumscribed, it includes such species as '' A. campestroides'', '' A. lamellidistans'', and '' A. variicystis''. * Section '' Cymbiformes'' He, Chuankid, Hyde, Cheewangkoon & Zhao :A section proposed in 2018, it is closely related to the traditional section ''Xanthodermatei''. The type species '' A. angusticystidiatus'' from
Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
is a smallish beige ''Agaricus'' with characteristic boat-shaped
basidiospore A basidiospore is a reproductive spore produced by basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid Ploidy () is the number of complete sets of chromos ...
s. It has a strong unpleasant smell like members of section ''Xanthodermatei'', but unlike these, its flesh does not change color when bruised, but turns dark reddish-brown when cut, and neither application of KOH nor Schäffer's test elicit a change in color. * Section '' Duploannulatae'' (also known as section '' Bivelares'' or '' Hortenses'') :Traditionally often included in section ''Agaricus'' as subsection ''Bitorques'', it seems to belong to a much younger radiation. It unites robust species, usually with a thick, almost fleshy ring, which inhabit diverse but often nutrient-rich locations. Some are well-known edibles; as they are frequently found along roads and in similar polluted places, they may not be safe to eat if collected from the wild. Their flesh is rather firm, white, with no characteristic smell, in some species turning markedly reddish when bruised or cut (though this may soon fade again), and generally changing color barely if at all after application of KOH or Schäffer's test. Based on DNA analysis of ITS1, ITS2, and 5.8S sequences, the studied species of this section could be divided into six distinct clades, four of which correspond to well-known species from the
temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
Northern Hemisphere: '' A. bisporus'', '' A. bitorquis'' (and the doubtfully distinct '' A. edulis''), '' A. cupressicola'' and '' A. vaporarius''. The other two clades comprise the '' A. devoniensis'' (including '' A. subperonatus'') and '' A. subfloccosus'' (including '' A. agrinferus'')
species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
es. Additional members of this section not included in that study are '' A. cappellianus'', '' A. cupressophilus'', '' A. subsubensis'', '' A. taeniatus'', '' A. tlaxcalensis'', and at least one undescribed species. The cultivated mushrooms traded as '' A. sinodeliciosus'' also belong here, though their relationship to the ''A. devoniensis'' complex and ''A. vaporarius'' is unclear. * Section '' Flocculenti'' :Includes '' A. erectosquamosus'' and '' A. pallidobrunneus''; a more distant undescribed relative of these two may also belong in this section. * Section '' Hondenses'' (disputed) :Traditionally included in section ''Xanthodermatei'' ''
sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...
'', this clade may be included therein as the most basal branch, or considered a section in its own right. It includes such species as '' A. biannulatus'', '' A. freirei'' and its North American relatives '' A. grandiomyces'', '' A. hondensis'', and probably also '' A. phaeolepidotus''. They are very similar to section ''Xanthodermatei'' ''
sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
'' in all aspects, except for a weaker discoloration tending towards reddish rather than
chrome yellow Chrome yellow is a bright, warm yellow pigment that has been used in art, fashion, and industry. It is the premier orange pigment for many applications. Production of chrome yellow and related pigments The raw pigment precipitates as a fine sol ...
when bruised. * Section '' Nigrobrunnescentes'' :Includes '' A. biberi'', '' A. caballeroi'', '' A. desjardinii'', '' A. erythrosarx'', '' A. fuscovelatus'', '' A. nigrobrunnescens'', '' A. padanus'', '' A. pattersoniae'', and probably also '' A. boisseletii''. * Section '' Rubricosi'' :Includes '' A. dolichopus'', '' A. kunmingensis'', '' A. magnivelaris'', '' A. variabilicolor'', and at least two undescribed species. * Section '' Sanguinolenti'' :Usually found in woodland. Brownish cap with a fibrous surface, typically felt-like but sometimes scaly. The fairly soft flesh turns pink, blood-red or orange when cut or scraped, in particular the outer layer of the stalk, but does not change color after application of KOH or Schäffer's test. Some North American species traditionally placed here, such as '' A. amicosus'' and '' A. brunneofibrillosus'', do not seem to be closely related to the section's type species '' A. silvaticus'' (including ''A. haemorrhoidarius'' which is sometimes considered a distinct species), and represent at least a distinct subsection. Other species often placed in this section are '' A. benesii'', '' A. dilutibrunneus'', '' A. impudicus'', '' A. koelerionensis'', '' A. langei'' and '' A. variegans''; not all of these may actually belong here. They are generally (though not invariably) regarded as edible and tasty. * Section '' Trisulphurati'' (disputed) :Includes the '' A. trisulphuratus'' species complex which is often placed in genus ''
Cystoagaricus ''Cystoagaricus'' is a genus of fungi in the family Psathyrellaceae. The genus contains four species found in subtropical America. The genus was circumscribed by mycologist Rolf Singer in 1947, with '' Cystoagaricus strobilomyces'' as the type spe ...
'', but seems to be a true ''Agaricus'' closely related to the traditional section ''Xanthodermatei''. Their stalk is typically bright yellow-orange, quite unlike that of other ''Agaricus'', as is the scaly cap. ''A. trisulphuratus'' was the type species of the obsolete
polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...
subgenus ''Lanagaricus'', whose former species are now placed in various other sections. * Section '' Xanthodermatei'' :As outlined by Singer in 1948, this section includes species with various characteristics similar to the type species '' A. xanthodermus''. The section forms a single
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
based on analysis of ITS1+2. They are either bright white all over, or have a cap densely flecked with brownish scales or tufts of fibers. The ring is usually large but thin and veil-like. Most inhabit woodland, and in general they have a more or less pronounced unpleasant smell of
phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...
ic compounds such as
hydroquinone Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a ''para' ...
. As food, they should all be avoided, because even though they are occasionally reported to be eaten without ill effect, the chemicals they contain give them a acrid, metallic taste, especially when cooked, and are liable to cause severe gastrointestinal upset. Their flesh at least in the lower stalk turns pale yellow to intensely reddish-ochre when bruised or cut; more characteristic however is the a bright yellow reaction with KOH while Schäffer's test is negative. Apart from ''A. xanthodermus'', the core group of this section contains species such as '' A. atrodiscus'', '' A. californicus'', '' A. endoxanthus'' and the doubtfully distinct '' A. rotalis'', '' A. fuscopunctatus'', '' A. iodosmus'', '' A. laskibarii'', '' A. microvolvatulus'', '' A. menieri'', '' A. moelleri'', '' A. murinocephalus'', '' A. parvitigrinus'', '' A. placomyces'', '' A. pocillator'', '' A. pseudopratensis'', '' A. tibetensis'', '' A. tollocanensis'', '' A. tytthocarpus'', '' A. xanthodermulus'', '' A. xanthosarcus'', as well as at least 4 undescribed species, and possibly '' A. cervinifolius'' and the doubtfully distinct '' A. infidus''. Whether such species as '' A. bisporiticus'', '' A. nigrogracilis'' and '' A. pilatianus'' are more closely related to the mostly
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
n core group, or to the more basal lineage here separated as section ''Hondenses'', requires clarification. Subgenus '' Spissicaules'' :The flesh of members of this subgenus tends to turn more or less pronouncedly yellowish in the lower stalk, where the skin is often rough and scaly, and reddish in the cap. They typically resemble the darker members of subgenus ''Flavoagaricus'', with a sweet smell and mild taste; like that subgenus, ''Spissicaules'' belongs to the smaller of the two main groups of the genus, but they form entirely different branch therein. While some species are held to be edible, others are considered unappetizing or even slightly poisonous. Also includes '' A. lanipes'' and '' A. maskae'', which probably belong to section ''Rarolentes'' or ''Spissicaules'', and possibly also '' A. bresadolanus'' and its doubtfully distinct relatives '' A. radicatus''/'' romagnesii''. * Section '' Amoeni'' :Includes '' A. amoenus'' and '' A. gratolens''. * Section '' Rarolentes'' :Includes '' A. albosquamosus'' and '' A. leucolepidotus''. * Section '' Spissicaules'' ( Hainem.) Kerrigan :Includes species such as '' A. leucotrichus''/'' litoralis'' (of which ''A. spissicaulis'' is a synonym, but see also Geml ''et al.'' 2004) and '' A. litoraloides''. Most significantly, some species have a persistent and unpleasant rotting-wood smell entirely unlike the sweet aroma of ''Flavoagaricus'', and while not known to be poisonous, are certainly unpalatable. * Section '' Subrutilescentes'' :Includes '' A. brunneopilatus'', '' A. linzhinensis'' and '' A. subrutilescens''. Somewhat similar to section ''Sanguinolenti'' or the dark-capped species of section ''Xanthodermatei'', but the flesh does not show a pronounced red or yellow color change when cut or bruised. Edibility is disputed.


Selected species

As late as 2008, ''Agaricus'' was believed to contain about 200 species worldwide but since then,
molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
studies have revalidated several disputed species, as well as resolved some
species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
es, and aided in discovery and description of a wide range of mostly tropical species that were formerly unknown to science. As of 2020, the genus is believed to contain no fewer than 400 species, and possibly many more. The medicinal mushroom known in Japan as
Echigoshirayukidake Echigoshirayukidake (Japanese language, Japanese: ), Common name, commonly called Basidiomycetes-X or BDM-X, is a sclerotium of ''Ceraceomyces tessulatus''. It is classified as a basidiomycete because of its beak-shaped processes (Clamp connecti ...
was initially also thought to be an ''Agaricus'', either a subspecies of ''Agaricus "blazei"'' (i.e. ''A. subrufescens''), or a new species. It was eventually identified as
sclerotium A sclerotium (; : sclerotia () is a compact mass of hardened fungal mycelium containing food reserves. One role of sclerotia is to survive environmental extremes. In some higher fungi such as ergot, sclerotia become detached and remain dormant u ...
of the crust-forming bark fungus ''
Ceraceomyces ''Ceraceomyces'' is a genus of fungi in the family Amylocorticiaceae Amylocorticiales is an order of fungi in the class Agaricomycetes. The order was circumscribed in 2010 to contain mostly resupinate (crust-like) forms that have been referred ...
tessulatus'', which is not particularly closely related to ''Agaricus''. Several
secotioid Secotioid fungi produce an intermediate fruiting body form that is between the mushroom-like hymenomycetes and the closed bag-shaped gasteroid fungi, gasteromycetes, where an evolutionary process of gasteromycetation has started but not run to co ...
(
puffball Puffballs are a type of fungus featuring a ball-shaped fruit body that (when mature) bursts on contact or impact, releasing a cloud of dust-like spores into the surrounding area. Puffballs belong to the division Basidiomycota and encompass sever ...
-like) fungi have in recent times be recognized as highly aberrant members of ''Agaricus'', and are now included here. These typically inhabit
desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
s where few fungiand even fewer of the familiar cap-and-stalk mushroom shapegrow. Another desert species, ''A. zelleri'', was erroneously placed in the present genus and is now known as ''
Gyrophragmium californicum ''Gyrophragmium'' is a genus of fungi in the family Agaricaceae. The genus was circumscription (taxonomy), circumscribed by French botanist Camille Montagne in 1843. The species known as ''G. dunalii'' was determined to properly belong into genu ...
''. In addition, the scientific names ''Agaricus'' and – even more so – ''Psalliota'' were historically often used as a "
wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the purpose of classifying organisms that do not fit anywhere else. They are typically defined by e ...
" for any and all similar mushrooms, regardless of their actual relationships. Species either confirmed or suspected to belong into this genus include: * ''
Agaricus abramsii ''Agaricus abramsii'' is a species of mushroom-forming fungus in the family Agaricaceae. It is endemic to the Santa Cruz Mountains of California, USA. It was first described described by mycologist William A. Murrill in 1912. It is notable for i ...
'' *  ''
Agaricus abruptibulbus ''Agaricus abruptibulbus'' is a species of mushroom in the genus ''Agaricus''. It is commonly known as the abruptly-bulbous agaricus or the flat-bulb mushroom. First described by the mycologist Charles Horton Peck, this bulbous-stemmed edible sp ...
'' – abruptly-bulbous agaricus, flat-bulb mushroom (disputed) *  '' Agaricus aestivalis'' * '' Agaricus agrinferus'' (disputed) * '' Agaricus alabamensis'' *  '' Agaricus albolutescens'' (disputed) * ''
Agaricus alligator ''Agaricus alligator'' is a species of mushroom-forming fungus in the family Agaricaceae. It is endemic to the US. It was first described in 1945. See also References {{Taxonbar, from=Q107470732 alligator An alligator, or colloquially ...
'' *  '' Agaricus amicosus'' * ''
Agaricus angusticystidiatus ''Agaricus angusticystidiatus'' is a species of fungus in the family Agaricaceae The Agaricaceae are a family of basidiomycete fungi and include the genus ''Agaricus'', as well as basidiomycetes previously classified in the families Tulostomat ...
'' * ''
Agaricus annae ''Agaricus annae'' is a species of mushroom in the genus ''Agaricus''.Pilát A. (1951). ''The Bohemian species of the genus'' Agaricus. Prague, 142 pp. This species is in the family Agaricaceae The Agaricaceae are a family of basidiomycete fun ...
'' * '' Agaricus arorae'' *  ''
Agaricus arvensis ''Agaricus arvensis'', commonly known as the horse mushroom, is a mushroom-forming fungus of the genus ''Agaricus''. Taxonomy It was described as ''Agaricus arvensis'' by Jacob Christian Schaeffer in 1774, and given numerous binomial descript ...
'' – horse mushroom *  ''
Agaricus augustus ''Agaricus augustus'', known commonly as the prince, is a basidiomycete fungus of the genus ''Agaricus''. It is generally edible, but bioaccumulates the metal cadmium. Taxonomy According to Heinemann's (1978) popular division of ''Agaricus'', ...
'' – the prince *  '' Agaricus aurantioviolaceus'' * '' Agaricus benesii'' *  ''
Agaricus bernardii ''Agaricus bernardii'', commonly called the salt-loving agaricus, or salty mushroom, is an agaric fungus in the family Agaricaceae. The mushroom's thick stipe (mycology), stem is usually shorter than the diameter of the Pileus (mycology), cap ...
'' – salt-loving mushroom *  ''
Agaricus bisporus ''Agaricus bisporus'', commonly known as the cultivated mushroom, is a basidiomycete mushroom native to grasslands in Eurasia and North America. It is cultivated in more than 70 countries and is one of the most commonly and widely consumed ...
'' – cultivated/button/portobello mushroom (includes ''A.brunnescens'') *  ''
Agaricus bitorquis ''Agaricus bitorquis'', commonly known as torq, banded agaric, spring agaric, banded agaricus, urban agaricus, or pavement mushroom, is an edible white mushroom of the genus ''Agaricus'', similar to the common button mushroom that is sold comm ...
'' – pavement mushroom, banded agaric * ''
Agaricus braendlei ''Agaricus braendlei'' is a common North American species of gilled mushroom closely related to the well known, typically old world species, '' A. campestris''.L.A. Parra & M.M. Gómez (2019). Micologia e Vegetazione Mediterranea 33 (2): 7 ...
'' * '' Agaricus bresadolanus'' *  ''
Agaricus brunneofibrillosus ''Agaricus brunneofibrillosus'', commonly known as the dusky mushroomhttps://www.britmycolsoc.org.uk/field_mycology/english-names or bleeding agaricus, is a mushroom in the family Agaricaceae. It has a medium to dark brown pileus (mycology), cap ...
'' (formerly in ''A.fuscofibrillosus'') *  ''
Agaricus californicus ''Agaricus californicus'', commonly known as the mock meadow mushroom, or California agaricus, is a species of fungus in the section (biology), section ''Xanthodermati'' of the genus ''Agaricus''. The mushroom is mildly mushroom poisoning, pois ...
'' – California agaricus *  ''
Agaricus campestris ''Agaricus campestris'' is a widely eaten gilled mushroom closely related to the cultivated '' A. bisporus'' (button mushroom). ''A. campestris'' is commonly known as the field mushroom or, in North America, meadow mushroom. It is ...
'' – field/meadow mushroom * '' Agaricus columellatus'' (formerly in ''Araneosa'') *  ''
Agaricus cupreobrunneus ''Agaricus cupreobrunneus'', commonly known as the copper mushrooomhttps://www.britmycolsoc.org.uk/field_mycology/english-names or brown field mushroom, is an edible mushroom of the genus ''Agaricus''. Description The brown cap is wide with ...
'' – brown field mushroom *  ''
Agaricus deserticola ''Agaricus deserticola'', commonly known as the gasteroid agaricus, is a species of fungus in the family Agaricaceae. Found only in southwestern and western North America, ''A. deserticola'' is adapted for growth in dry or semi-arid habitats ...
'' G.Moreno, Esqueda & Lizárraga (2010) – gasteroid agaricus (formerly in ''Longula'') *  ''
Agaricus dulcidulus ''Agaricus dulcidulus'' is a small mushroom in the family Agaricaceae of the order Agaricales, found in deciduous woodlands of Europe, but also recorded in North America, North Africa and Asia. The English name is rosy wood mushroom. Despite th ...
'' – rosy wood mushroom (sometimes in ''A.semotus'') *  ''
Agaricus excellens ''Agaricus excellens'' (French language, French: Psaliote Excellente, German language, German: Riesen-Egerling) is a rare European mushroom in the genus ''Agaricus''. Description * Cap: It is whitish yellow in color. Spread over across, it ...
'' (disputed) * '' Agaricus freirei'' *  ''
Agaricus hondensis ''Agaricus hondensis'', commonly known as the felt-ringed agaricus, is a species of fungus in the family Agaricaceae. The species was officially described in 1912 by mycologist William Alphonso Murrill, along with three other ''Agaricus'' specie ...
'' – felt-ringed agaricus *  ''
Agaricus impudicus ''Agaricus impudicus'', also known as the tufted wood mushroom, is a mushroom of ''Agaricus'', a genus with many edible species. Description As with all ''Agaricus'' species, gills are free, colour progresses with age from pale-pink to a chocol ...
'' – tufted wood mushroom * ''
Agaricus inapertus ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom ...
'' (formerly in ''Endoptychum'') * ''
Agaricus julius ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom (' ...
'' * ''
Agaricus lanatoniger ''Agaricus lanatoniger'' is an agaric fungus in the family Agaricaceae, endemic to New Zealand. Taxonomy ''A. lanatoniger'' was first described in 1974 by Belgian mycologist Paul Heinemann and collected by Egon Horak in December 1967. The hol ...
'' * '' Agaricus langei'' (= ''A.fuscofibrillosus'') *  '' Agaricus lilaceps'' – giant cypress agaricus * '' Agaricus litoralis'' – coastal mushroom (includes ''A.spissicaulis'') *  ''
Agaricus macrosporus ''Agaricus macrosporus'' is a rare, edible mushroom found from June at wood fringes and in meadows. Description The white cap is hemispherical and white when young, but later flattens out up to in diameter and becomes yellowish or tan. Its fle ...
'' (disputed) *   ''
Agaricus moelleri ''Agaricus moelleri'', commonly known as the inky mushroom, or dark scaled mushroom, is a large species of fungus in the genus ''Agaricus''. It appears occasionally in most kinds of woodland, during late summer, in northern temperate zones. Tax ...
'' – inky/dark-scaled mushroom (formerly in ''A.placomyces'', includes ''A.meleagris'') * '' Agaricus nebularum'' *  ''
Agaricus pattersoniae ''Agaricus pattersoniae'' is an edible mushroom, edible species of mushroom. It is found in the United States, where it associates with Cupressus macrocarpa, cypress trees. It has been proposed for inclusion in the IUCN Red List of Threatened Sp ...
'' *  '' Agaricus perobscurus'' – American princess *  ''
Agaricus phaeolepidotus ''Agaricus phaeolepidotus'' (dusky scaled mushroom https://www.britmycolsoc.org.uk/field_mycology/english-names is a species of fungus in the family Agaricaceae. A European species, the agaric was first species description, described scientifical ...
'' *  '' Agaricus pilatianus'' *  '' Agaricus placomyces'' (includes ''A.praeclaresquamosus'') *  ''
Agaricus pocillator ''Agaricus pocillator'', a woodland mushroom, is distributed through southeastern North America in ranges at least as far north as Illinois. It can be distinguished in the field by its dark center, its small, bulbous base, which stains yellow, a ...
'' *  ''
Agaricus santacatalinensis ''Agaricus santacatalinensis'' is a species of agaric fungus. Described as new to science in 1998 by Edgardo Albertó, it is found in deciduous forests of Brazil, where it grows under privets (''Ligustrum'') and elm (''Ulmus''). The fruit bodies ...
'' *  ''
Agaricus semotus ''Agaricus semotus'' is a woodland mushroom of the fungus order ''Agaricales''. Like many of its relatives, it can be found spread throughout wooded, moist areas in the southern United States, and has been found in areas ranging from California t ...
'' *  '' Agaricus silvaticus'' – scaly/blushing wood mushroom, pinewood mushroom (= ''A.sylvaticus'', includes ''A.haemorrhoidarius'') *  ''
Agaricus silvicola ''Agaricus silvicola'', also known as the wood mushroom or woodland agaricus, is a species of Agaricus mushroom related to the button mushroom. Taxonomy Originally described as the variety ''Agaricus campestris'' var. ''silvicola'' by Carlo V ...
'' – wood mushroom (= ''A.sylvicola'') *  '' Agaricus subrufescens'' (includes ''A.rufotegulis'', often confused with ''A.blazei'' and ''A.brasiliensis'') – almond mushroom, royal sun agaricus, and various fanciful names *  ''
Agaricus subrutilescens ''Agaricus subrutilescens'', also known as the wine-colored agaricus, is a mushroom of the genus ''Agaricus''. Taxonomy The species was first described scientifically in 1925 as ''Psalliota subrutilescens''. It was transferred to ''Agaricus'' ...
'' – wine-colored agaricus * '' Agaricus taeniatus'' *  ''
Agaricus urinascens ''Agaricus urinascens'' (the macro mushroom) is a species of fungus in the family Agaricaceae. The mushroom grows up to wide and tall. The cap is whitish, domed then becoming convex in age. The gills are whitish, then darken to pink or brownis ...
'' *  ''
Agaricus xanthodermus ''Agaricus xanthodermus'', commonly known as the yellow-staining agaricus, yellow-staining mushroom or yellow-stainer, is a species of fungus in the genus ''Agaricus''. It displays a strong yellow colouration at the base of the stem when cut. It ...
'' – yellow-staining mushroom


Description

Members of ''Agaricus'' are characterized by having a fleshy cap or pileus, from the underside of which grow a number of radiating plates or
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 ...
, on which are produced the naked
spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...
s. They are distinguished from other members of their family,
Agaricaceae The Agaricaceae are a family of basidiomycete fungi and include the genus ''Agaricus'', as well as basidiomycetes previously classified in the families Tulostomataceae, Lepiotaceae, and Lycoperdaceae. Taxonomy The family Agaricaceae was publishe ...
, by their chocolate-brown spores. Members of ''Agaricus'' also have a stem or stipe, which elevates it above the object on which the mushroom grows, or
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
, and a
partial veil In mycology, a partial veil (also called an inner veil, to differentiate it from the "outer", or universal veil) is a temporary structure of tissue found on the fruiting bodies of some Basidiomycota, basidiomycete fungus, fungi, typically agarics. ...
, which protects the developing gills and later forms a ring or annulus on the stalk.


Toxicity

A notable group of poisonous ''Agaricus'' is the
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
around the yellow-staining mushroom, '' A. xanthodermus''. One species reported from Africa, '' A. aurantioviolaceus'', is reportedly deadly poisonous. Far more dangerous is the fact that ''Agaricus'', when still young and most valuable for eating, are easily confused with several deadly species of ''
Amanita The genus ''Amanita'' contains about 600 species of agarics, including some of the most toxic known mushrooms found worldwide, as well as some well-regarded Edible mushroom, edible species (and many species of unknown edibility). The genus is re ...
'' (in particular the species collectively called "
destroying angel The name destroying angel applies to several similar, closely related species of deadly all-white mushrooms in the genus ''Amanita''. They are '' Amanita virosa'' in Europe and '' A. bisporigera'' and '' A. ocreata'' in eastern and western North ...
s", as well as the white form of the appropriately-named "death cap" ''
Amanita phalloides ''Amanita phalloides'' ( ), commonly known as the death cap, is a deadly poisonous basidiomycete fungus and mushroom, one of many in the genus ''Amanita''. Originating in Europe but later introduced to other parts of the world since the late ...
''), as well as some other highly poisonous fungi. An easy way to recognize ''Amanita'' is the gills, which remain whitish at all times in that genus. In ''Agaricus'', by contrast, the gills are only initially white, turning dull pink as they mature, and eventually the typical chocolate-brown as the spores are released. Even so, ''Agaricus'' should generally be avoided by inexperienced collectors, since other harmful species are not as easily recognized, and clearly recognizable mature ''Agaricus'' are often too soft and maggot-infested for eating. When collecting ''Agaricus'' for food, it is important to identify every individual specimen with certainty, since one ''Amanita'' fungus of the most poisonous species is sufficient to kill an adult human – even the shed spores of a discarded specimen are suspected to cause life-threatening poisoning. Confusing poisonous ''Amanita'' with an edible ''Agaricus'' is the most frequent cause of fatal
mushroom poisoning Mushroom poisoning is poisoning resulting from the ingestion of mushrooms that contain toxicity, toxic substances. Signs and symptoms, Symptoms can vary from slight Gastrointestinal tract, gastrointestinal discomfort to death in about 10 days. Mus ...
s world-wide. Reacting to some distributors marketing dried agaricus or agaricus extract to cancer patients, it has been identified by the U.S.
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...
as a "fake cancer 'cure. The species most often sold as such
quack cure Quackery, often synonymous with health fraud, is the promotion of fraudulent or Ignorance, ignorant medicine, medical practices. A quack is a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or public ...
s is ''A. subrufescens'', which is often referred to by the erroneous name "Agaricus Blazei" and advertised by fanciful trade names such as "God's mushroom" or "mushroom of life", but can cause allergic reactions and even liver damage if consumed in excessive amounts.


Uses

The genus contains the most widely consumed and best-known mushroom today, '' A. bisporus''. Other well-known and highly regarded species include '' A. arvensis'', '' A. augustus'', and '' A. campestris''. ''
Agaricus porphyrocephalus ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom (' ...
'' is a choice edible when young, while '' A. subrufescens'' may be edible in some cases. Many other species are of culinary value, especially within sections ''Agaricus'', ''Arvense'', ''Duploannulatae'' and ''Sanguinolenti''.


References


Sources

* *


External links


Mushroom Expert - The Genus Agaricus
{{Authority control Agaricales genera Taxa named by Carl Linnaeus Taxa described in 1753