Friesia 4:204. 1952.
Common Name: none
Cap 2.5-6 cm broad, convex, expanding to nearly plane; margin at first inrolled, then decurved, plane to upturned at maturity; surface dry, the disc sometimes tomentose, becoming appressed squamulose, brown to greyish-brown, occasionally tinged vinaceous, the squamules often raised near the margin giving a shaggy aspect, obscurely squamulose to merely appressed fibrillose in age or from weathering; flesh thin, soft, pallid, discoloring slowly to pale dull-brown when injured; not yellowing in KOH; odor and taste mild.
Gills free, close, moderately broad, dingy-pink when young, blackish-brown at maturity.
Stipe 1.5-3.5 cm long, 1-1.5 cm thick, straight, round, equal or narrowed at the base, stuffed to hollow at maturity; surface pallid, smooth with scattered flattened scales at the apex, minutely scaly below, often nearly glabrous in age, sometimes discoloring brownish where handled; veil cottony-membranous, thin, whitish, forming an inconspicuous, short, erect, medial to superior ring.
Spores 7-8 x 5-6 µm, elliptical, smooth, thick-walled; spore print blackish-brown.
Scattered to gregarious in disturbed ground: along paths, in sparse grass, vacant lots etc., fruiting from early fall to mid-winter.
Edible, of good flavor.
This modest-sized Agaricus is characterized by a brown, appressed, squamulose cap, inconspicuous ring, and a preference for fruiting in disturbed areas, i.e. overgrazed pastures, impoverished lawns and roadsides. Agaricus campestris, with which it sometimes fruits, can be distinguished by a nearly white, smooth (except in dry weather) cap, and even more evanescent ring. Several other Agaricus species with brown, scaly caps occur in our area, but all are either considerably larger, bruise yellow or red, have distinctive odors (phenol or anise), or occur in forest habitats.
Breitenbach, J. & Kränzlin, F. (1995). Fungi of Switzerland. Volume 4: Agarics (2nd Part). Entolomataceae, Pluteaceae, Amanitaceae, Agaricaceae, Coprinaceae, Strophariaceae. Verlag Mykologia: Luzern, Switzerland. 368 p.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Kerrigan, Richard W. (1986). The Agaricales (Gilled Fungi) of California. 6. Agaricaceae. Mad River Press: Eureka, CA. 62 p.
Sánchez, L.A.P. (2008). Agaricus L.; Allopsalliota Nauta & Bas; Tribu Agariceae S. Imai: Part 1. Edizioni Candusso: Alassio, Italy. 824 p.