Persoonia 5(4): 419. 1969
Common Name: none
Cap 70-140 mm broad, convex, becoming plano-convex; margin incurved, then decurved, frequently decorated with cottony veil fragments when young; surface white to cream, covered with white, powdery to cottony floccose universal veil fragments, sometimes forming small pyramidal warts that developing buff tones in age and are easily removed; ornamentation sometimes lost at maturity leaving the surface glabrous, moist to subviscid; context white, unchanging, soft, up to 10 mm in width near disc; odor mild when young, unpleasant in age; taste mild.
Gills narrowly attached to free, close, cream colored, unchanging, relatively broad, up to 10 (15) mm in width, edges fimbriate; lamellulae in three to four series.
Stipe 70-170 x 20-40 mm in width, round, solid, equal to gradually enlarged or sub-bulbous at the base with a pointed root-like extension; surface dry, white, obscurely fibrillose at apex, elsewhere sparsely covered with cottony universal veil fragments sometimes discoloring tan brown; annulus absent, or if present, ephemeral; volva poorly developed, consisting of concentric bands of veil fragments discoloring buff brown to pinkish brown.
Spores 10.5-12 (12.5) x 6.5-9.0 µm, broadly ellipsoid to ovoid, smooth, thin-walled, hilar appendage inconspicuous; amyloid; spores white in deposit
Solitary or in small groups under pines in the San Francisco Bay Area and in mixed hardwood-conifer woods along the north coast, possibly associated with Douglas Fir (Pseudotsuga menziesii); also likely at mid elevations of the Sierra Nevada; fruiting from fall to mid-winter; uncommon in most years.
Deadly poisonous!!! Symptoms include nausea and vomiting beginning 2-12 hours after ingestion and progresses to kidney failure in 2-6 days.
Amanita smithiana is a beautiful white, uncommon Amanita recognized by a cap with soft, white powdery-floccose to occasionally small pyramidal shaped warts that readily slough off and maybe absent in age. The cottony, friable universal veil also often leaves fragments on the young cap margin and along the stipe, but seldom forms an annulus. A rudimentary volva in the form of bands of universal veil tissue develops at the base of the stipe which typically has a root-like extension.
While not as lethal as the death cap, Amanita phalloides, A. smithiana is dangerously poisonous, known to cause kidney failure. Poisonings have been reported in Oregon and Washington where it has inadvertently been collected by hunters of matsutake (Tricholoma magnivelare). Though the two species are superficially similar, they are relatively easy to distinguish using a combination of characters. These include stature, relatively tall in Amanita smithiana versus stocky in Tricholoma magnivelare; the presence of well-developed cottony veil cap fragments (at least in youth) in Amanita smithiana, absent in Tricholoma magnivelare; the presence of a membranous and persistent annulus in Tricholoma magnivelare, normally absent in Amanita smithiana; the presence of bands of scale-like rings at the base of the stipe along with a root-like extension in Amanita smithiana (if carefully collected), absent in Tricholoma magnivelare; finally, the presence of a spicy odor in Tricholoma magnivelare compared to a mild in young specimens of Amanita smithiana, becoming unpleasant in age.
Amanita smithiana should be compared with several other whitish California Amanitas. These include the white form of the death cap, Amanita phalloides (see that description for details); Amanita magniverrucata, recognized by large, white to tan, firmly anchored pyramidal cap warts; Amanita cokeri, smilar to A. magniverrucata but with small persistent tan-colored warts, and Amanita silvicola, similar to Amanita smithiana with floccose cap patches, but differing in possessing a marginate, bulbous base and mild odor. Finally it should be noted that Amanita ocreata, a deadly oak-dwelling species, and spring counterpart to the fall fruiting Amanita phalloides, has a cream colored, usually glabrous cap that resembles the cap of Amanita smithiana if its universal veil has sloughed off.
Bas, C. (1969). Morphology and Subdivision of Amanita and a Mongraph of its Section Lepidella. Persoonia 5: 285-579. (Protologue)
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Duffy, T.J. (2008). Toxic Fungi of Western North America. MykoWeb.
Thiers, Harry D. (1982). The Agaricales (Gilled Fungi) of California. 1. Amanitaceae. Mad River Press: Eureka, CA. 53 p.
Tulloss, R. E. and J. E. Lindgren. (1992). Amanita smithiana—taxonomy, distribution, and poisonings. Mycotaxon 45: 373-387.
West, P., Lindgren, J. & Horowitz, B. (2009). Amanita smithiana mushroom ingestion: A case of delayed renal failure and literature review. Journal of Medical Toxicology 5(1): 32-38.