''Agaricus placomyces'' is a toxic basidiomycete fungus of the genus Agaricus. It is found in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

; 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. The flesh is white, and becomes yellow when placed in KOH. The gills of this mushroom are free from the

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

, 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 ''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 ...

''). 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. 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 A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. ...

, 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. Agaricus

The

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s are 4–6.0 x 3.5–4.5

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

, smooth, and elliptical; the spore print is blackish-brown.

Toxicity

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

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

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

s. Unlike many other ''Agaricus'' species, it fruits from mid to late winter rather than during the late spring, summer and early fall.''Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi'' ; By David Arora, Edition: 2, illustrated; Published by Ten Speed Press, 1986; , page 329.

References

Sources

mushroomexpertrogermushrooms
{{Taxonbar, from=Q2669175 placomyces Fungi described in 1878 Fungi of North America Poisonous fungi Taxa named by Charles Horton Peck

Description

Toxicity

Habitat

See also

References

Sources