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Agaricus hondensis

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Agaricus hondensis
Agaricus hondensis 71317.jpg
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Agaricaceae
Genus: Agaricus
Species: A. hondensis
Binomial name
Agaricus hondensis
Murrill (1912)

Agaricus bivelatoides Murrill (1912)
Agaricus hillii Murrill (1912)
Agaricus macmurphyi Murrill (1912)
Agaricus glaber Zeller (1938)[1]

Agaricus hondensis
View the Mycomorphbox template that generates the following list
Mycological characteristics
gills on hymenium

cap is convex

or flat
hymenium is free
stipe has a ring

spore print is brown

to purple-brown
ecology is saprotrophic
edibility: poisonous

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 species that have since been placed in synonymy with A. hondensis. Found in the Pacific Northwest region of North America, A. hondensis fruits in the fall under conifers or in mixed forests.

The fungus produces fruit bodies (mushrooms) with white to gray-brown caps up to 15 cm (6 in) in diameter covered with pale pinkish-brown scales that darken in age. The tightly-packed gills on the cap underside are initially white before becoming pinkish, lilac-gray, and finally brownish as the spores mature. The stout stipe is bulbous and has a thick, white, felt-like ring. The mushroom is poisonous, and causes severe gastrointestinal upset if consumed. It has an unpleasant odor similar to phenol or creosote, and develops a soapy-metallic taste when cooked. Agaricus hondensis can be distinguished from similar Agaricus species by differences in geographic range, habitat, staining reaction, and odor.


The species was first described as new to science by American mycologist William Alphonso Murrill in 1912, based on collections he made in November, 1911 under Californian redwoods. In the same publication, Murrill also described the species Agaricus bivelatoides, A. hillii, and A. macmurphyi, all from the Pacific Northwest region of North America. The latter two were named to honor their original collectors, Albert Hill and James Ira Wilson McMurphy, respectively, while the former was named for its resemblance to A. bivelatus.[3] In 1944, Alexander H. Smith examined the type material of several of Murrill's species, and concluded that were no characters to separate A. hondensis from A. bivelatoides, A. hillii, or A. macmurphyi. He also determined that Sanford Myron Zeller's A. glaber, published as new in 1938,[1] was also the same species as A. hondensis.[4] The nomenclatural database MycoBank considers these names synonymous.[2] The epithet hondensis refers to the type location, La Honda, California.[3] The mushroom is commonly known as the "felt-ringed agaricus".[5]

Agaricus hondensis has traditionally been classified in the section Xanthodermatei, a grouping of Agaricus species related to A. xanthodermus that are characterized by fruit bodies with phenolic odors, temporary yellowing discolorations in some parts of the fruit body, a negative Schaeffer’s reaction, and toxicity. A molecular analysis has shown that it, along with the related species A. freirei and A. phaeolepidotus, comprise a basal lineage in a clade of related sylvan species that have weak yellowing reactions and some tendencies toward reddish bruising reactions. This lineage is closely related to a group of Agaricus species that are typically placed in the section Sanguinolenti. Phylogenetic evidence suggests that these three species belong to a clade that diverged shortly after the presumed split of the sections Xanthodermatei and Duploannulati.[6]


The thick, skirtlike ring flares outward from the stipe.

The cap is initially convex before flattening out, and reaches a diameter of 6–15 cm (2.4–5.9 in). The dry and smooth cap surface is whitish or has pale pinkish-brown to pinkish-gray to fawn-colored flattened fibrils or fine fibrillose scales (at least in the center). In maturity, the fibrils usually darken to brown, reddish-brown, or reddish-gray, but in one northern form the fibrils are darker brown from the beginning. The flesh is thick and white. When bruised or injured, the flesh either does not change color, or may stain pale yellowish, then often slowly discolors pinkish. The odor of the crushed flesh is mild or faintly phenolic, but is usually distinctly phenolic in the base of the stipe.[7]

The gills are initially pale pinkish to pinkish-gray before becoming brown, then chocolate-brown or darker when the spores mature. In maturity, the gills are free from attachment to the stipe, and are packed close together with little intervening spaced between them. The stipe is 7–20 cm (2.8–7.9 in) long, and 1–2.5 cm (0.4–1.0 in) thick but with a thicker or bulbous base. Firm, smooth, and lacking the scales found on the cap, the stipe is white but discolors dingy pinkish or brownish in age or after handling. The flesh in the extreme base usually stains pale yellowish when bruised. The partial veil is membranous, white, and forms a thick, felt-like ring on the upper portion of the stipe. The ring is skirtlike but often flares outward instead of collapsing against the stipe.[7] A drop of dilute potassium hydroxide placed on the cap turns yellow.[8]

Agaricus hondensis spores (1000x)

Spore prints are purplish brown to chocolate brown. The smooth, thick-walled spores are broadly ellipsoidal, and typically measure 5.8–7.3 by 3.7–4.4 μm. The basidia (spore-bearing cells) are four-spored, club-shaped, hyaline (translucent, and measure 20–21.3 by 5.8–7.0 μm. Cystidia on the gill edge (cheilocystidia) are sac-shaped to club-shaped, hyaline to pale yellowish brown in color, and have dimensions of 18.3–25.6 by 7.3–11.0 μm; there are no cystidia on the gill face (pleurocystidia).[5]

Similar species[edit]

Distinctive field characteristics of Agaricus hondensis include its woodland habitat, the yellow staining reaction with KOH, and its odor.[9] Agaricus freirei closely resembles A. hondensis, and, based on similarities in DNA sequences, is a close relative.[6] A. freirei is found in coastal regions of Spain.[10] A. hondensis has also been confused with A. silvaticus and A. placomyces.[5] A. sylvaticus does not have foul-smelling flesh, and has a negative KOH reaction.[11] A. placomyces is found from the midwestern United States eastward.[12] Another lookalike, the edible A. subrutilescens, has similar overall coloration, but is distinguished from A. hondensis by a mild odor, a shaggy stipe, and a less substantial ring.[13]

Habitat and distribution[edit]

A saprobic species,[8] the fruit bodies of Agaricus hondensis grow scattered or in groups under conifers or in mixed forests.[13] They have also been reported to grow in fairy rings.[8] The fungus is found in the Pacific Coast of North America, from British Columbia in Canada south to California,[14] but is most common in California.[13] The mushroom fruits in the fall from September to October throughout much of its range, but in California the fruiting season tends to be from November to February.[9]


Agaricus hondensis mushrooms are toxic, and consuming the fruit bodies causes gastroenteritis.[15] Some fruit bodies smell of creosote, an odor that becomes even more prevalent if the mushrooms are cooked. Cooking also introduces an unpleasant soapy-metallic flavor.[5] The fruit bodies are used as food by the vagrant shrew (Sorex vagrans) and the American shrew mole (Neurotrichus gibbsii).[16] Relatively high levels of the chemical hydroquinone are present in fruit bodies.[17]

See also[edit]


  1. ^ a b Zeller SM (1938). "New or noteworthy agarics from the Pacific Coast States". Mycologia. 30 (4): 468–74. JSTOR 3754471. doi:10.2307/3754471. 
  2. ^ a b "Agaricus hondensis Murrill 1912". MycoBank. International Mycological Association. Retrieved 2012-07-13. 
  3. ^ a b Murrill WA (1912). "The Agaricaceae of the Pacific Coast – III. Brown and black-spored genera". Mycologia. 4 (6): 294–308. doi:10.2307/3753286. 
  4. ^ Smith AH (1944). "Interesting North American Agarics". Bulletin of the Torrey Botanical Club. 71 (4): 390–409. JSTOR 2481312. 
  5. ^ a b c d Ammirati J, Traquair JA, Horgen PA (1985). Poisonous Mushrooms of the Northern United States and Canada. Ottawa, Canada: Fitzhenry & Whiteside in cooperation with Agriculture Canada. p. 226. ISBN 978-0-88902-977-4. 
  6. ^ a b Kerrigan RW, Callac P, Guinberteau J (2005). "Agaricus section Xanthodermatei: a phylogenetic reconstruction with commentary on taxa". Mycologia. 97 (6): 1292–315. PMID 16722221. doi:10.3852/mycologia.97.6.1292. 
  7. ^ a b Arora D. (1986). Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi. Berkeley, California: Ten Speed Press. pp. 326–7. ISBN 978-0-89815-169-5. 
  8. ^ a b c Kuo M. (February 2005). "Agaricus hondensis". Retrieved 2014-01-04. 
  9. ^ a b Lincoff G. (1981). The Audubon Society Field Guide to North American Mushrooms. New York, New York: Knopf. p. 507. ISBN 978-0-394-51992-0. 
  10. ^ Blanco-Dios JB. (2001). "Agaricales des dunes de Galice (nord-ouest de l'Espagne). 1. Agaricus freirei Blanco-Dios, sp. nov.". Documents Mycologiques (in French). 31 (127): 27–34. 
  11. ^ Noordeloos ME, Kuyper TW, Vellinga EC (2001). Flora Agaricina Neerlandica. 5. CRC Press. p. 39. ISBN 978-90-5410-495-7. 
  12. ^ McKnight VB, McKnight KH (1987). A Field Guide to Mushrooms: North America. Peterson Field Guides. Boston, Massachusetts: Houghton Mifflin. p. 259. ISBN 978-0-395-91090-0. 
  13. ^ a b c Ammirati J, Trudell S (2009). Mushrooms of the Pacific Northwest. Timber Press Field Guides. Portland, Oregon: Timber Press. p. 190. ISBN 978-0-88192-935-5. 
  14. ^ Schalkwijk-Barendsen HME. (1991). Mushrooms of Western Canada. Edmonton, Canada: Lone Pine Publishing. p. 330. ISBN 978-0-919433-47-2. 
  15. ^ Barceloux DG (2008). Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs, Plants, and Venomous Animals. John Wiley & Sons. p. 291. ISBN 978-0-470-33557-4. 
  16. ^ Terry CJ (1978). "Food habits of three sympatric species of insectovora in western Washington". Canadian Field-Naturalist. 92: 38–44. 
  17. ^ Jovel E, Kroeger P, Towers N (1996). "Hydroquinone: the toxic compound of Agaricus hondensis". Planta Medica. 62 (2): 195. PMID 17252436. doi:10.1055/s-2006-957852. 

External links[edit]