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*Agaricus placomyces*
Mycological characteristics
Agaricus placomyces Mycological characteristics
	Gills on hymenium
	Cap is convex or flat
	Hymenium is free
	Stipe has a ring
	Spore print is blackish-brown
	Ecology is saprotrophic
	Edibility is poisonous

Agaricus placomyces
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Agaricaceae
Genus:	Agaricus
Species:	A. placomyces
Binomial name
	Agaricus placomyces; Peck (1878)
Synonyms
	Agaricus praeclaresquamosus A.E.Freeman 1979); Fungus placomyces (Peck) Kuntze (1898); Psalliota placomyces (Peck) Lloyd (1899)

Agaricus placomyces is a toxic basidiomycete fungus of the genus Agaricus. It is found in North America; the Eurasian populations formerly known by the same scientific name are nowadays known as A. moelleri, while the present species may also be referred to as A. praeclaresquamosus.

Description

Agaricus placomyces has a cap that is 5–12 cm and varies from convex to broadly convex or nearly flat in age. In addition, the surface of the cap is dry and covered with brownish fibers and scales, especially over the center. Underneath, the cap can be whitish under normal environments, or pinkish in wet weather. Covered with fine, appressed greyish-brown scales and concentrated at the disc, the cap is thick, slowly becoming vinaceous when injured; the odor smells of phenol.^[1] The flesh is white, and becomes yellow when placed in KOH.^[2]

The gills of this mushroom are free from the stem, crowded, and pale grayish-pink, turning brown in age. In addition, the stem is 6–15 cm long, 1–1.5 cm. thick and more or less equal, with an enlarged base (unlike typically ending in a small bulb like Agaricus pocillator). Also, it is fairly smooth, white and bruising yellow, especially at the base, with a persistent ring, and the partial veil when still covering the gills developing brownish to yellowish droplets.^[3]^[4]

At 8–15 cm long and 2–3.5 cm thick, the stipe is slightly enlarged at the base; the surface is white, and smooth above and below the ring. The veil of the stipe is membranous, thick, white, and forms a persistent ring with a smooth upper and lower surface. The base of the stipe is typically yellow when bruised and smells of phenol.^[5]

Yellow staining rhizomorphs at the base of *Agaricus placomyces* specimens

The spores are 4–6.0 x 3.5–4.5 μm, smooth, and elliptical; the spore print is blackish-brown.

Toxicity

Agaricus placomyces contains toxins which cause gastrointestinal upset,^[1] as with other phenolic-odored Agaricus species. Some people reportedly may not be affected.^[6] The mushroom's taste is mild and its odor resembles phenol or coal tar.^[1]

Habitat

Agaricus placomyces is saprobic. In addition, it grows in groups under hardwoods and in mixed woods during summer and fall. It is generally found east of the Rocky Mountains and northern in distribution. Generally, it is solitary, living in either small groups, or clusters on disturbed ground under conifers. Unlike many other Agaricus species, it fruits from mid to late winter rather than during the late spring, summer and early fall.^[7]^[8]

References

^ ^a ^b ^c Miller Jr., Orson K.; Miller, Hope H. (2006). North American Mushrooms: A Field Guide to Edible and Inedible Fungi. Guilford, CN: FalconGuide. p. 278. ISBN 978-0-7627-3109-1.
^ Kuo, Michael (January 2018). "Agaricus placomyces (MushroomExpert.Com)". www.mushroomexpert.com. Retrieved 2024-11-23.
^ Breitenbach & Kränzlin (vol. 4): sp. 188 Archived April 24, 2009, at the Wayback Machine
^ Freeman, A.E.H. (1979). Agaricus in the southeastern United States. Mycotaxon 8(1): 50–118.
^ Kerrigan, Richard W. (1986). The Agaricales (Gilled Fungi) of California. 6. Agaricaceae. Mad River Press: Eureka, CA. 62 p.
^ Phillips, Roger (2010). Mushrooms and Other Fungi of North America. Buffalo, NY: Firefly Books. p. 225. ISBN 978-1-55407-651-2.
^ Kerrigan, R.W., Callac, P., Guinberteau, J., Challen, M.P. & Parra, L. (2005). Agaricus section Xanthodermatei: a phylogenetic reconstruction with commentary on taxa. Mycologia 97: 1292–1315.
^ Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi ; By David Arora, Edition: 2, illustrated; Published by Ten Speed Press, 1986; ISBN 0-89815-169-4, ISBN 978-0-89815-169-5 page 329.