Clav. Syn. Hym. Europ. 89. 1878.
Common Name: none
Cap 7-16 cm broad, convex at first, margin incurved, becoming plane, disk frequently depressed at maturity; surface white, smooth, though typically with warts or cottony scales. Cap tissue turning reddish-orange when cut. Odor, of brine or iodine.
Gills free, close, pinkish-tan becoming chocolate brown, finally blackish brown.
Stipe 4-7 cm long, 3-4.5 cm thick, smooth, narrower at base; veil membranous, sheathing the stipe base, forming a medial ring.
Spores 5.5-7.0 x 5.5-6.5 µm, smooth elliptical. Spore print blackish-brown.
Found spring, summer and fall primarily in grassy areas, sandy soils, occasionally under Monterey cypress; gregarious sometimes forming arcs but rarely complete fairy-rings. In grass it often fruits with Agaricus californicus, A. arvensis, Marasmius oreades, and Leucoagaricus naucinus.
Edible and excellent, although the briny taste deters some people.
Agaricus bernardii is a short, stocky, white mushroom that resembles Agaricus bitorquis, even possessing a sheathing veil and a propensity for partial emergence. However, it can easily be told apart by the reddish-brown staining of cap and stipe tissue as well as its briny odor. Along the coast, particularly in sandy soils, Agaricus bernardii is considerably more common than A. bitorquis.
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.