Agaricus of North America: 154. 2016.
Common Name: none
Misapplied names: Agaricus placomyces Peck; Agaricus meleagris (Schaeff.) Pilát; Agaricus praeclaresquamosus Freeman
Cap 7-19 cm broad, cylindrical to convex, expanding to nearly plane in age; surface dry, ground color pallid to white, covered with fine, appressed greyish-brown scales, concentrated at the disc; flesh white, thick, slowly becoming vinaceous when injured; odor strongly of phenol; yellowing in KOH.
Gills free, close, at first whitish, then pink, finally blackish-brown.
Stipe 8-15 cm long, 2-3.5 cm thick, equal to slightly enlarged at base; surface white, smooth above and below the ring; veil membranous, thick, white, upper and lower surface smooth, forming a medially positioned, persistent ring; stipe base typically yellowing when bruised and smelling of phenol.
Spores 4-6.0 x 3.5-4.5 µm, smooth, elliptical; spore print blackish-brown.
Solitary, in small groups, or cespitose clusters on disturbed ground under conifers; fruiting from early to mid-winter.
Toxic; like other phenolic-odored Agaricus species, it can cause gastrointestinal upsets.
Agaricus deardorffensis is a large, strikingly beautiful mushroom which unfortunately for the mycophagist, is toxic. Its squamulose cap and stature resemble Agaricus augustus, an excellent edible, but the latter has tawny-brown not grey-brown cap scales, an anise, not phenol odor, and the flesh does not discolor vinaceous-brown. Additionally, Agaricus deardorffensis fruits from mid to late winter, while A. augustus fruits usually during the late spring, summer and early fall.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Freeman, A.E.H. (1979). Agaricus in the southeastern United States. Mycotaxon 8(1): 50-118.
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. (Protologue)
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.
Smith, A.H. (1949). Mushrooms in their Natural Habitats. Sawyer's Inc: Portland, OR. 626 p.