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Amanita virosiformis

[ Basidiomycota > Agaricales > Amanitaceae > Amanita . . . ]

by Michael Kuo

Associated with oaks in the southeastern United States, Amanita virosiformis is a member of the "destroying angel" species group (see Amanita bisporigera for the best-known North American representative). Like other species in the group it features white colors, a sac-like volva at the base of the stem, and a large, white ring. However, Amanita virosiformis differs in having a terrible, rotten-meat-like odor and, under the microscope, elongated spores.

Amanita tenuifolia is a synonym.

Thanks to Thane Taylor for documenting, collecting, and preserving Amanita virosiformis for study; his collection is deposited in The Herbarium of Michael Kuo.


Ecology: Mycorrhizal with oaks in sandy soil, often in pine-oak woods; late spring through fall; originally described from Gainesville, Florida; distributed along the lower Atlantic Coast of the United States, as well as the Gulf Coast, to eastern Texas. The illustrated and described collection is from Florida.

Cap: 5–9 cm across; convex, expanding to broadly convex or planoconvex; bald; tacky when fresh; white to whitish, with a slightly brownish center at maturity; with or without one to several flat, whitish patches; the margin not lined.

Gills: Free from the stem or nearly so; white; close; short-gills present.

Stem: 6–10 cm long; 1–2 cm thick; fairly equal above a swollen, mostly underground base 3–4 cm thick; dry; finely silky; white; with a large white ring and a sac-like white volva.

Flesh: White; unchanging when sliced.

Odor: Strong and unpleasant, especially in dried specimens.

Microscopic Features: Spores 12–14 x 5–6.5 µm; elongated-ellipsoid; smooth; hyaline in KOH; amyloid. Basidia about 20 x 5 µm; clavate; 4-sterigmate. Hymenial cystidia not found. Pileipellis an ixocutis of smooth, hyaline elements 2.5–5 µm wide, with patches of velar sphaerocysts.

REFERENCES: (W. A. Murrill, 1941) W. A. Murrill, 1941. (Murrill, 1945; Kimbrough, 1972; Jenkins, 1986; Tulloss & Possiel, 2005; Tulloss, continuously updated.) Herb. Kuo 08302001.

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Amanita virosiformis

Amanita virosiformis

Amanita virosiformis

Amanita virosiformis

Amanita virosiformis

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Kuo, M. (2020, December). Amanita virosiformis. Retrieved from the MushroomExpert.Com Web site: