Bull. Torrey Bot. Club 25: 370. 1898.
Common Name: none
Cap 50-80 mm broad, convex, maturing plano-convex, often centrally depressed; margin decurved to upturned in age, occasionally wavy, inconspicuously striate; surface glabrous, subviscid when moist, peelable a short distance from the margin, white to cream, buff-colored at the disc; context white, unchanging, soft at maturity, up to 10 mm thick near the disc; odor indistinct, taste weak to moderately acrid.
Gills adnexed to adnate, close, subdistant at maturity, brittle, white, becoming cream, unchanging, edges even, 8-10 mm in width, seldom forked; lamellulae uncommon.
Stipe 30-60 x 15-20 (25) mm in width, equal, straight, round, brittle; surface white, unchanging, obscurely fibrillose-striate; context soft, white, unchanging; partial veil absent.
Spores 6.5-9.5 x 6-7.5 µm, subglobose to ovoid or broadly ellipsoid, ornamentation amyloid, composed of low warts, thin lines with occasional heavier ridges, not reticulate.
Solitary to scattered in small groups, mostly under liveoak (Quercus agrifolia) in the San Francisco Bay Area, also reported from mixed hardwood-conifer coastal forests and low elevations of the Sierra Nevada; fruiting from after the fall rains to mid-winter; common.
Russula albidula is broadly interpreted here to describe what commonly occurs under oaks in the San Francsico Bay area. It is recognized by a cream-colored, glabrous, slightly striate-margined cap, mild to moderate acrid taste, white gills that soon become cream, and non-reticulate spores that are cream-yellow in deposit. It is often confused with Russula cremoricolor, but the latter has white gills and spores and a more acrid taste. Other cream-colored species include Russula burgeae, known only from Jackson State Forest in Mendocino Co., recognized by a tuberculate-striate cap margin, mild taste, cream-colored gills and spores that are partially reticulate. Russula albida also differs with a tuberculate-striate cap margin, but with white gills and spores. Other cream-colored species include Russula ochroleuca, with usually whitish spores that have a nearly complete reticulum; R. crenulata, also with whitish spores, but with finely serrated gill edges (thus the species epithet); and R. raoultii, an acrid species with nearly completely reticulate white spores. Finally another oak-dwelling Russula sometimes found with Russula albidula is Russula basifurcata. It has a cream-colored cap typically tinged pinkish, at least near the margin, cream gills and spores, and a mild taste. Reflecting the species name, the gills are often forked near the stipe. None of the above is known to have culinary value.
Murrill, W.A. (1907-1916). North American Flora: (Agaricales) Polyporaceae-Agaricaceae. 9: 1-542.
Peck, C.H. (1898). New species of Alabama fungi. Bull. Torrey bot. Club 25(7): 368-328.