Mycologia 30: 219. 1938.
Common Name: wine colored Agaricus
Cap 6-14 cm broad, convex, expanding to plano-convex to nearly flat in age, sometimes with a low umbo; margin at first incurved, becoming decurved, occasionally upturned; surface dry, when young, dark-brown to purple-brown, appressed fibrillose or with flattened scales, darkest at disc, becoming paler towards the margin as a whitish ground color is revealed; flesh white, unchanging, thick, firm when young; odor and taste mild; pileal surface turning green in KOH.
Gills free, close, moderately broad, pinkish-brown, bruising reddish-brown, blackish-brown at maturity.
Stipe 6-16 cm long, 1-2 cm thick, stuffed/hollow, equal to somewhat enlarged at base; surface more or less smooth at the apex, covered with cottony scales below; veil membranous, upper surface striate, lower surface white, cottony-fibrillose, forming a thin, membranous, superior ring.
Spores 4-6.0 x 3.5-4.5 µm, smooth, elliptical; spore print blackish-brown.
Solitary, scattered to sometimes in arcs in mixed hardwood-conifer woods; fruiting from early to mid-winter.
Edible and good.
Agaricus subrutilescens is recognized by a dark-brown to purple-brown, appressed fibrillose-scaly cap, stipe with conspicuous cottony scales below the ring, and forest habit. It is most likely to be confused with Agaricus hondensis, a toxic species, with which it sometimes fruits. The latter, however, has a cap with tan to buff-brown scales, a thicker ring, and a bulbous base. If in doubt, KOH will give a yellowing reaction in Agaricus hondensis while the pileus of A. subrutilescens will turn green.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Kerrigan, R.W. (1986). The Agaricales (Gilled Fungi) of California. 6. Agaricaceae. Mad River Press: Eureka, CA. 62 p.
Kerrigan, R.W. (2016). Agaricus of North America. New York Botanical Garden: Bronx, NY. 574 p.
Smith, A.H. (1949). Mushrooms in their Natural Habitats. Sawyer's Inc: Portland, OR. 626 p.