Agaricus is agenus ofmushroom-formingfungi containing bothedible andpoisonous species, with over 400 members worldwide[2][3] 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 dominantcultivated mushrooms of the West.
1855 field notes with synonymy ofHypophyllum (quoted literature) withOmphalia andAgaricus (added handwritten notes)
Several origins of genus nameAgaricus have been proposed. It possibly originates from ancientSarmatia Europaea, where people Agari, promontory Agarum and a river Agarus were known (all located on the northern shore ofSea of Azov, probably, near modernBerdiansk in Ukraine).[4][5][6]
Note also Greekἀγαρικόν, agarikón, "a sort of tree fungus" (There has been anAgaricon Adans. genus, treated by Donk inPersoonia 1:180.)
For many years, members of the genusAgaricus were given the generic namePsalliota, and this can still be seen in older books on mushrooms. All proposals to conserveAgaricus againstPsalliota or vice versa have so far been considered superfluous.[7]
Donk reportsCarl Linnaeus' name is devalidated (so the proper author citation apparently is "L. per Fr., 1821") becauseAgaricus was not linked to Tournefort's name. Linnaeus places bothAgaricus Dill. andAmanita Dill. in synonymy, but truly a replacement forAmanita Dill., which would requireA. quercinus, notA. campestris be the type. This question is compounded becauseElias Magnus Fries himself usedAgaricus roughly in Linnaeus' sense (which leads to issues withAmanita), andA. campestris was eventually excluded fromAgaricus by Karsten and was apparently inLepiota at the time Donk wrote this, commenting that a type conservation might become necessary.[8]
The alternate name for the genus,Psalliota, derived from theGreekpsalion/ψάλιον, "ring", was first published by Fries (1821) as trib.Psalliota. The type isAgaricus campestris (widely accepted, except by Earle, who proposedA. cretaceus).Paul Kummer (not Quélet, who merely excluded Stropharia) was the first to elevate the tribe to a genus.Psalliota was the tribe containing the type ofAgaricus, so when separated, it should have caused the rest of the genus to be renamed, but this is not what happened.[9]
The use ofphylogenetic analysis to determine evolutionary relationships amongstAgaricus 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 genusAgaricus, as circumscribed byRolf Singer, 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.[10]Restriction fragment length polymorphism analysis demonstrated this classification scheme needed revision.[11]
This is the group around thetype species of the genus, the popular edibleA. campestris which is common across theHolarctictemperate zone, 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 asA. 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 ofKOH, orSchäffer's test (aniline andHNO3).A. annae may also belong here, as mightA. 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 subgenusPseudochitonia, in particular sectionChitonioides. TheA. bresadolanus/radicatus/romagnesii group which may be one or several species is sometimes placed here, but may be quite distinct and belong to subgenusSpissicaules.
Traditionally contained about 20 rather large species similar to the horse mushroomA. arvensis in six subgroups. Today, several additional species are recognized – in particular in theA. arvensisspecies complex – and placed here, such asA. aestivalis,A. augustus,A. caroli,A. chionodermus,A. deserticola (formerlyLongula texensis),A. fissuratus,A. inapertus (formerlyEndoptychum depressum),A. macrocarpus,A. nivescens,A. osecanus,A. silvicola and the doubtfully distinctA. essettei,A. urinascens, and the disputedtaxaA. abruptibulbus,A. albertii,A. altipes,A. albolutescens,A. brunneolus,A. excellens andA. macrosporus. It also includesA. subrufescens which started to be widely grown and traded under various obsolete and newly-invented names in the early 21st century, as well as theFloridanA. blazei with which theBrazilianA. subrufescens was often confused in the past. They have versatileheterothallic life cycles,[15] are found in a variety of often ratherarid 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 ormarzipan due tobenzaldehyde and derived compounds distinguishes them from the sectionXanthodermatei, 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 accumulatecadmium and other highly toxic chemicals from the environment, and may not always be safe to eat.
A group of buff-white to reddish-brown species. Often delicate and slender, the typical members of this subgenus do not resemble the largerAgaricus 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, typicallyalmond-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 asA. aridicola (formerly known asGyrophragmium dunalii),A. colpeteii,A. columellatus (formerlyAraneosa columellata),A. diminutivus,A. dulcidulus,A. lamelliperditus,A. luteomaculatus,A. porphyrizon,A. semotus andA. xantholepis are included here, but delimitation to and indeed distinctness from subgenusFlavoagaricus is a long-standing controversy. Unlike these however, subgenusMinores 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.
Somewhat reminiscent of subgenusMinores and like it closely related to subgenusFlavoagaricus, it contains species such asA. martinicensis andA. rufoaurantiacus.
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 poisonousAgaricus, and some of its sections are in overall appearance more similar to the more distantly relatedAgaricus proper andFlavoagaricus than to their own closest relatives. Some species in this subgenus, such asA. goossensiae andA. rodmanii, are not yet robustly assigned to one of the sections.
IncludesA. bohusii which resembles one of the dark-cappedFlavoagaricus orXanthodermatei 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 includeA. crassisquamosus,A. haematinus, andA. pseudolangei.
Contains species such asA. bernardii and the doubtfully distinctA. bernardiiformis,A. gennadii,A. nevoi,A. pequinii,A. pilosporus andA. rollanii, which strongly resemble the members of sectionDuploannulatae 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 pronouncedumami-like, in some even intensely so. Some are edible and indeed considered especially well-tasting, while the unusualA. maleolens which may also belong here has an overpowering aroma which renders it inedible except perhaps in small amounts as a veganfish sauce substitute.
A section proposed in 2018, it is closely related to the traditional sectionXanthodermatei. The type speciesA. angusticystidiatus fromThailand is a smallish beigeAgaricus with characteristic boat-shapedbasidiospores. It has a strong unpleasant smell like members of sectionXanthodermatei, 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.[14]
Traditionally often included in sectionAgaricus as subsectionBitorques, 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 ofITS1, ITS2, and5.8S sequences, the studied species of this section could be divided into six distinct clades, four of which correspond to well-known species from thetemperate Northern Hemisphere:A. bisporus,A. bitorquis (and the doubtfully distinctA. edulis),A. cupressicola andA. vaporarius. The other two clades comprise theA. devoniensis (includingA. subperonatus) andA. subfloccosus (includingA. agrinferus)species complexes.[17] Additional members of this section not included in that study areA. cappellianus,A. cupressophilus,A. subsubensis,A. taeniatus,A. tlaxcalensis, and at least one undescribed species.[18] The cultivated mushrooms traded asA. sinodeliciosus also belong here, though their relationship to theA. devoniensis complex andA. vaporarius is unclear.
Traditionally included in sectionXanthodermateisensu lato, this clade may be included therein as the mostbasal branch, or considered a section in its own right. It includes such species asA. biannulatus,A. freirei and its North American relativesA. grandiomyces,A. hondensis, and probably alsoA. phaeolepidotus. They are very similar to sectionXanthodermateisensu stricto in all aspects, except for a weaker discoloration tending towards reddish rather thanchrome yellow when bruised.
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 asA. amicosus andA. brunneofibrillosus, do not seem to be closely related to the section's type speciesA. silvaticus (includingA. haemorrhoidarius which is sometimes considered a distinct species), and represent at least a distinct subsection. Other species often placed in this section areA. benesii,A. dilutibrunneus,A. impudicus,A. koelerionensis,A. langei andA. variegans; not all of these may actually belong here. They are generally (though not invariably) regarded as edible and tasty.
Includes theA. trisulphuratus species complex which is often placed in genusCystoagaricus, but seems to be a trueAgaricus closely related to the traditional sectionXanthodermatei. Their stalk is typically bright yellow-orange, quite unlike that of otherAgaricus, as is the scaly cap.A. trisulphuratus was the type species of the obsoletepolyphyletic subgenusLanagaricus, whose former species are now placed in various other sections.
As outlined by Singer in 1948, this section includes species with various characteristics similar to the type speciesA. xanthodermus.[19] The section forms a singleclade based on analysis of ITS1+2.[20] 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 ofphenolic compounds such ashydroquinone. 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 fromA. xanthodermus, the core group of this section contains species such asA. atrodiscus,A. californicus,A. endoxanthus and the doubtfully distinctA. 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 possiblyA. cervinifolius and the doubtfully distinctA. infidus. Whether such species asA. bisporiticus,A. nigrogracilis andA. pilatianus are more closely related to the mostlyEurasian core group, or to the more basal lineage here separated as sectionHondenses, requires clarification.
Agaricus lanipes(F.H.Møller & Jul.Schäff. 1938) Hlaváček 1949 ex Pilát/Singer 1951
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 subgenusFlavoagaricus, 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 includesA. lanipes andA. maskae, which probably belong to sectionRarolentes orSpissicaules, and possibly alsoA. bresadolanus and its doubtfully distinct relativesA. radicatus/romagnesii.
Includes species such asA. leucotrichus/litoralis (of whichA. spissicaulis is a synonym, but see also Gemlet al. 2004[13]) andA. litoraloides. Most significantly, some species have a persistent and unpleasant rotting-wood smell entirely unlike the sweet aroma ofFlavoagaricus, and while not known to be poisonous, are certainly unpalatable.
IncludesA. brunneopilatus,A. linzhinensis andA. subrutilescens. Somewhat similar to sectionSanguinolenti or the dark-capped species of sectionXanthodermatei, but the flesh does not show a pronounced red or yellow color change when cut or bruised. Edibility is disputed.
As late as 2008,Agaricus was believed to contain about 200 species worldwide[21] but since then,molecular phylogenetic studies have revalidated several disputed species, as well as resolved somespecies complexes, 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.
Themedicinal mushroom known in Japan asEchigoshirayukidake was initially also thought to be anAgaricus, either a subspecies ofAgaricus "blazei"[22] (i.e.A. subrufescens), or a new species.[23] It was eventually identified assclerotium of the crust-forming bark fungusCeraceomyces tessulatus, which is not particularly closely related toAgaricus.
Severalsecotioid (puffball-like) fungi have in recent times be recognized as highly aberrant members ofAgaricus, and are now included here. These typically inhabitdeserts where few fungi – and even fewer of the familiar cap-and-stalk mushroom shape – grow. Another desert species,A. zelleri, was erroneously placed in the present genus and is now known asGyrophragmium californicum. In addition, the scientific namesAgaricus and – even more so –Psalliota were historically often used as a "wastebasket taxon" for any and all similar mushrooms, regardless of their actual relationships.
Species either confirmed or suspected to belong into this genus include:
Agaricus subrufescens (includesA.rufotegulis, often confused withA.blazei andA.brasiliensis) – almond mushroom, royal sun agaricus, and various fanciful names
Members ofAgaricus are characterized by having a fleshy cap orpileus, from the underside of which grow a number of radiating plates orgills, on which are produced the nakedspores. They are distinguished from other members of their family,Agaricaceae, by their chocolate-brown spores. Members ofAgaricus also have a stem or stipe, which elevates it above the object on which the mushroom grows, orsubstrate, and apartial veil, which protects the developing gills and later forms a ring orannulus on the stalk.
The white form of thedeath capAmanita is often mistaken for edibleAgaricus, with fatal results
A notable group of poisonousAgaricus is theclade around the yellow-staining mushroom,A. xanthodermus.[24]One species reported from Africa,A. aurantioviolaceus, is reportedly deadly poisonous.[25]
Far more dangerous is the fact thatAgaricus, when still young and most valuable for eating, are easily confused with several deadly species ofAmanita (in particular the species collectively called "destroying angels", as well as the white form of the appropriately-named "death cap"Amanita phalloides), as well as some other highly poisonous fungi. An easy way to recognizeAmanita is the gills, which remain whitish at all times in that genus. InAgaricus, 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 matureAgaricus are often too soft and maggot-infested for eating. When collectingAgaricus for food, it is important to identify every individual specimen with certainty, since eating just oneAmanita mushroom cap can cause serious illness.
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 as a"fake cancer 'cure'".[26] The species most often sold as suchquack cures isA. 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.[27]
The genus contains the most widely consumed and best-known mushroom today,A. bisporus. Other well-known and highly regarded species includeA. arvensis,[28]A. augustus, andA. campestris.[29]Agaricus porphyrocephalus is a choice edible when young,[30] whileA. subrufescens may be edible in some cases. Many other species are of culinary value, especially within sectionsAgaricus,Arvense,Duploannulatae andSanguinolenti.[12][31]
^Bas C. (1991). A short introduction to the ecology, taxonomy and nomenclature of the genusAgaricus, 21–24. In L.J.L.D. Van Griensven (ed.),Genetics and breeding ofAgaricus. Pudoc, Wageningen, The Netherlands.
^W. Smith, ed. (1854)."Agari".Dictionary of Greek and Roman Geography. Vol. I. Boston: Little, Brown, and Company. p. 72. (on Google Books,on archive.org)
^Wakesfield E. (1940). "Nomina genérica conservando. Contributions from the Nomenclature Committee of the British Mycological Society, III".Transactions of the British Mycological Society.24 (3–4):282–293.doi:10.1016/s0007-1536(40)80028-4.
^Donk, M.A. (1962). "The generic names proposed for Agaricaceae".Beihefte zur Nova Hedwigia.5:1–320.ISSN0078-2238.
^Donk, M.A. (1962). "The generic names proposed for Agaricaceae". Beihefte zur Nova Hedwigia 5: 1–320. ISSN 0078-2238
^Singer, Rolf (1987).Agaricales in Modern Taxonomy. Lubrecht & Cramer Ltd.ISBN978-3-7682-0143-8.
^Bunyard BA, Nicholson MS, Royse DJ (December 1996). "Phylogeny of the genusAgaricus inferred from restriction analysis of enzymatically amplified ribosomal DNA".Fungal Genet Biol.20 (4):243–53.doi:10.1006/fgbi.1996.0039.PMID9045755.
^Challen MP, Kerrigan RW, Callac P (2003). "A phylogenetic reconstruction and emendation ofAgaricus section Duploannulatae".Mycologia.95 (1):61–73.doi:10.2307/3761962.JSTOR3761962.PMID21156589.
^Kerrigan RW, Callac P, Parra LA (2008). "New and rare taxa inAgaricus sectionBivelares (Duploannulati)".Mycologia.100 (6):876–92.doi:10.3852/08-019.PMID19202842.S2CID25519596.
^Singer R (1948). "Diagnoses Fungorum Novorum Agaricalium".Sydowia.2:26–42.
^Kerrigan RW, Callac P, Guinberteau J, Challen MP, Parra LA (2005). "Agaricus sectionXanthodermatei: a phylogenetic reconstruction with commentary on taxa".Mycologia.97 (6):1292–315.doi:10.3852/mycologia.97.6.1292.PMID16722221.
^Kirk PM, Cannon PF, Minter DW, Stalpers JA (2008).Dictionary of the Fungi (10th ed.). Wallingford, UK: CAB International. p. 13.ISBN978-0-85199-826-8.
^US 6120772A, Hitoshi Ito & Toshimitsu Sumiya, "Oral drugs for treating AIDS patients", issued 2000-09-19
^Buczacki, Stefan; Shields, Chris; Ovenden, Denys (2012).Collins Fungi Guide: The most complete field guide to the mushrooms and toadstools of Britain & Ireland. HarperCollins UK. p. 49.ISBN9780007242900.
^Walleyn R; Rammeloo J. (1994).The Poisonous and Useful Fungi of Africa South of the Sahara. Scripta Botanica Belgica. Vol. 10. National Botanic Garden of Belgium. p. 10.ISBN978-90-72619-22-8.
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