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Agaricus pocillator

[ Basidiomycetes > Agaricales > Agaricaceae > Agaricus . . . ]

Taxonomy in Transition: ...  > Agaricales > Lepiotoid Clade (J&V, 1998)

by Michael Kuo

This woodland mushroom is distributed through southeastern North America, and ranges at least as far north as Illinois. It can be distinguished in the field by its (usually) dark center, its relatively slight stature, and its small, bulbous base, which stains yellow, inside and out. Agaricus placomyces is very similar, but is a slightly larger mushroom with a scalier cap and a more northern range. See the comments below for more help separating the two species.


Ecology: Saprobic; growing alone or gregariously under hardwoods and in mixed woods; summer and fall; eastern and southeastern North America.

Cap: 3-10 cm; convex to broadly convex or nearly flat in age, sometimes with an obscure, darker bump; dry; whitish to dingy, developing vaguely concentric brownish to grayish scales towards the center.

Gills: Free from the stem; close; white, becoming pinkish, then brown.

Stem: 4-8 cm long; .5-1 cm. thick; more or less equal; with a small bulbous base that bruises yellow; with a ring that typically persists into maturity; partial veil when covering the gills not developing dark droplets.

Flesh: White throughout; staining bright yellow in the base.

Odor and Taste: Taste not distinctive or somewhat unpleasant; odor often unpleasant (phenolic), but sometimes not distinctive.

Spore Print: Brown.

Chemical Reactions: Cap and flesh yellow with KOH.

Microscopic Features: Spores 4.5-6 x 3-3.8 µ; elliptical.

REFERENCES: Murrill, 1941. (Freeman, 1979; Weber & Smith, 1985; Phillips, 1991/2005; Kerrigan et al., 2005.) Herb. Kuo 06099601, 09020102, 07140309, 06290701.

Several authors emphasize the width of the spores when separating Agaricus pocillator from Agaricus placomyces (the latter having broadly elliptical spores measuring 5-7 x 3.5-5 µ; the former with skinnier, elliptical spores measuring 4.5-6 x 3-4 µ). This seems unnecessarily arcane to me--and, more importantly, potentially inaccurate. In my collections, spore width ranges from 3-5 µ for both species, but important macrofeatures do not vary. Agaricus placomyces is somewhat larger and stockier than Agaricus pocillator, and has more brown scales and fibers away from the disc. Additionally, it lacks the small, abrupt bulb at the stem base and often (though not always) has brownish or yellowish droplets on the underside of the partial veil when it is still covering the gills. When the droplets have dried out, the veil is discolored--whereas the veil of Agaricus pocillator lacks droplets and is never discolored.

Further Online Information:

Agaricus pocillator at Roger's Mushrooms


Agaricus pocillator

Agaricus pocillator

Agaricus pocillator

Agaricus pocillator

Agaricus pocillator

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Kuo, M. (2007, May). Agaricus pocillator. Retrieved from the MushroomExpert.Com Web site: