Toxic Fungi of Western North America

by Thomas J. Duffy, MD

Amanita smithiana poisoning & unclassified renal/hepatic toxicity

Amanita smithiana Bas, which is found frequently in coastal forests of Northern California and the PNW contains toxins quite different from those present in other Amanita species. The appearance of Amanita smithiana is somewhat variable and is similar to some other white species of Amanita. Amanita smithiana is usually seen in the fall, but it also occurs in the spring. The base of the stipe, even without much of a “root” or “bulb” is unevenly swollen much like the root of a horse-radish. (116)

Amanita smithiana
Amanita smithiana photo © Darvin DeShazer

Amanita smithiana is white with a convex/expanded or centrally depressed, subviscid when moist, 6-16 cm wide cap. There may be no special odor, but in age there is often an unpleasant meaty odor. Janet Lindgren notes that the taste is mild to somewhat sweet. The cap has no striations, but has white floccose to flattened bits of universal veil tissue on it or hanging from the edge. In age, these floccules tend to disappear and the cap becomes smooth like Amanita ocreata. The white to pinkish-buff gills typically reach the stipe and so the specimen may be not recognized immediately as an Amanita since Amanita gills are typically free. The edges of the gills are finely irregular or minutely floccose, a feature best appreciated with a hand lens. The ring is poorly formed and may collapse on the stipe. The white stipe may bruise pinkish buff or brownish and is thicker at the base, which tends to split and may have a root-like portion. The volva is poorly formed and usually consists of one or two white rings at the base of the stipe, often evanescent.

Amanita smithiana is usually seen in the fall, but it also occurs in the spring. The species occurs in pine and mixed conifer forests from the northern Mexican highlands to coastal British Columbia. Amanita smithiana has also been reported from Idaho, Arizona and New Mexico and presumably may be found in the adjacent states. Amanita smithiana may be confused at times with the so-called “matsutake” or Tricholoma magnivelare (Armillaria ponderosa). Trichloma magnivelare has a delicious spicy odor; a more persisting (although also collapsing) cottony ring on the stipe, no volva and the flesh is unusually firm. Amanita smithiana, in contrast, is fairly fragile and may have no odor or a slightly pungent to “meaty” odor, becoming unpleasant in age.