Agaricus

Genus of mushrooms


title: "Agaricus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["agaricus", "agaricales-genera", "fungal-taxa-named-by-carl-linnaeus", "taxa-described-in-1753"] description: "Genus of mushrooms" topic_path: "general/agaricus" source: "https://en.wikipedia.org/wiki/Agaricus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of mushrooms ::

| image = Agaricus-campestris-michoacan.jpg | image_caption = The type species Agaricus campestris (field or meadow mushroom) | taxon = Agaricus | authority = L. (1753) | subdivision_ranks = Species | subdivision = | diversity = 400 species | diversity_link = List of Agaricus species | type_species = Agaricus campestris | type_species_authority = L. (1753) | synonyms_ref = | synonyms = {{plainlist|

  • Amanita Dill. ex Boehm. (1760)
  • Araneosa
  • Fungus Tourn. ex Adans. (1763)
  • Hypophyllum Paulet (1808)
  • Longula Zeller (1945)
  • Myces Paulet (1808)
  • Agaricus trib. Psalliota Fr. (1821)
  • Pratella (Pers.) Gray (1821)
  • Psalliota (Fr.) P.Kumm. (1871)

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 (A. bisporus) and the field mushroom (A. campestris), the dominant cultivated mushrooms of the West.

Taxonomy

::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/96/Iconographie_des_champignons_de_Paulet_(Pl.LXXXIX)(6266440221).jpg" caption="1855 field notes with synonymy of ''Hypophyllum '' (quoted literature) with ''Omphalia'' and ''Agaricus'' (added handwritten notes)"] ::

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, probably, near modern Berdiansk in Ukraine).

Note also Greek ἀγαρικόν, 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.

Donk reports Carl Linnaeus' 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 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 psalion/ψάλιον, "ring", was first published by Fries (1821) as trib. Psalliota. The type is Agaricus campestris (widely accepted, except by Earle, who proposed A. 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 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 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, 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 analysis demonstrated this classification scheme needed revision.

Subdivisions

As of 2018, this genus is divided into 6 subgenera and more than 20 sections:

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/ad/Cupreobrunneus.jpg" caption="A. cupreobrunneus]]'' ''(Jul.Schäff. & Steer 1939) Pilát 1951''"] ::

'*Subgenus *Agaricus'''''

  • '*Section *Agaricus''''' :This is the group around the type species of the genus, the popular edible A. campestris which is common across the Holarctic temperate 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 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 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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/5d/Agaricus_osecanus_110729w.jpg" caption="''[[Agaricus osecanus]] Pilát 1951''"] ::

'*Subgenus *Flavoagaricus'''''

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/07/Agaricus_diminutivus_706380.jpg" caption="''[[Agaricus diminutivus]] Peck 1873''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/2e/Agaricus_comtulus_G4.jpg" caption="''[[Agaricus comtulus]] Fr. 1836/1838''"] ::

'*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-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 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.

'*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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c0/Agaricus_bohusii_(33229461686).jpg" caption="''[[Agaricus bohusii]] Bon 1983''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/6/63/2012-07-09_Agaricus_subfloccosus_235732_crop.jpg" caption="''[[Agaricus subfloccosus]]''(J.E.Lange 1926) Hlaváček/Pilát 1951"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/89/Agaricus_cappellianus_268349.jpg" caption="''[[Agaricus cappellianus]]'' ''Hlaváček 1987''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/0d/Agaricus_hondensis_Murrill_377257.jpg" caption="Felt-ringed agaricus, ''[[Agaricus hondensis]] Murrill 1912''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c5/Agaricus_pattersonae_112211.jpg" caption="Agaricus pattersoniae]] Peck 1907''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/84/2014-05-22_Cystoagaricus_trisulphuratus_(Berk.)_Singer_421894.jpg" caption="''[[Agaricus trisulphuratus]] Berk. 1885''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/85/Agaricus_xanthoderma_eF.jpg" caption="Yellow-staining mushroom, ''[[Agaricus xanthodermus]] Genev. 1876''"] ::

'*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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/3/3d/Agaricus_lanipes_20121012w.JPG" caption="''[[Agaricus lanipes]]''(F.H.Møller & Jul.Schäff. 1938) Hlaváček 1949 ex Pilát/Singer 1951"] ::

'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.

Selected species

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/bd/Agaricus_alligator_Murrill_323415.jpg" caption="''[[Agaricus alligator]]'' Murrill 1945"] ::

Main article: List of Agaricus species

As late as 2008, Agaricus was believed to contain about 200 species worldwide but since then, molecular phylogenetic studies have revalidated several disputed species, as well as resolved some species 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.

The medicinal mushroom known in Japan as Echigoshirayukidake 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 of the crust-forming bark fungus Ceraceomyces tessulatus, which is not particularly closely related to Agaricus.

Several secotioid (puffball-like) fungi have in recent times be recognized as highly aberrant members of Agaricus, and are now included here. These typically inhabit deserts 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. In addition, the scientific names Agaricus 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:

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, on which are produced the naked spores. They are distinguished from other members of their family, Agaricaceae, 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, and a partial veil, which protects the developing gills and later forms a ring or annulus on the stalk.

Toxicity

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/03/Amanita_fhaloides._var.blanca-_panoramio.jpg" caption="The white form of the [[death cap]] ''Amanita'' is often mistaken for edible ''Agaricus'', with fatal results"] ::

A notable group of poisonous Agaricus is the clade 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 (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 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 eating just one Amanita 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. The species most often sold as such quack cures 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 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

References

  1. Bas C. (1991). A short introduction to the ecology, taxonomy and nomenclature of the genus ''Agaricus'', 21–24. In L.J.L.D. Van Griensven (ed.), ''Genetics and breeding of ''Agaricus. Pudoc, Wageningen, The Netherlands.
  2. Capelli A. (1984). ''Agaricus''. L.: Fr. (Psalliota Fr.). ''Liberia editrice Bella Giovanna'', Saronno, Italy
  3. Donk, M.A.. (1962). "The generic names proposed for Agaricaceae". Beihefte zur Nova Hedwigia.
  4. Donk, M.A. (1962). "The generic names proposed for Agaricaceae". Beihefte zur Nova Hedwigia 5: 1–320. ISSN 0078-2238
  5. Singer, Rolf. (1987). "Agaricales in Modern Taxonomy". Lubrecht & Cramer Ltd.
  6. (December 1996). "Phylogeny of the genus ''Agaricus'' inferred from restriction analysis of enzymatically amplified ribosomal DNA". Fungal Genet Biol.
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  9. (2018). "A new section and species of Agaricus subgenus Pseudochitonia from Thailand". [[MycoKeys]].
  10. (2003). "A phylogenetic reconstruction and emendation of ''Agaricus'' section Duploannulatae". Mycologia.
  11. Singer R. (1948). "Diagnoses Fungorum Novorum Agaricalium". Sydowia.
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  17. "187 Fake Cancer 'Cures' Consumers Should Avoid". U.S. [[Food and Drug Administration]].
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  19. (2006). "North American Mushrooms: A Field Guide to Edible and Inedible Fungi". [[FalconGuide]].
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  22. Wakesfield E.. (1940). "Nomina genérica conservando. Contributions from the Nomenclature Committee of the British Mycological Society, III". Transactions of the British Mycological Society.
  23. (1994). "The Poisonous and Useful Fungi of Africa South of the Sahara". National Botanic Garden of Belgium.
  24. (2004). "Molecular evolution of ''Agaricus'' species based on ITS and LSU rDNA sequences". Mycological Progress.
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  26. (27 March 2018). "The genus Agaricus in the Caribbean. Nine new taxa mostly based on collections from the Dominican Republic". Magnolia Press.

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