Amanita spreta

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by Michael Kuo

Common in the southeast and occasional in the Great Lakes region and northeastern North America, Amanita spreta is distinguished by its grayish brown cap with dark, radial streaks; its medium to large size; the presence of a ring on the upper stem; and its stem base, which features a white, sacklike volva and is not prominently swollen. Its ellipsoid, inamyloid spores also help to distinguish it.

"Amanita spreta" may represent a group of potential North American species that share the features emphasized above. Amanita expert Rodham Tulloss features several spreta-like, unnamed potential species in his key to northeastern Amanita species (2013)--and many field guide authors treat Amanita spreta as a group of similar species.

A flaring, "lobed" volva is often found on the stem base of Amanita spreta, and the wide V shape featured in the photo to the right can be seen in many field guide illustrations. Though it is not a feature mentioned in technical descriptions I have seen, the flaring volva may serve as a good secondary field character for identification.

Description:

Ecology: Mycorrhizal with hardwoods and conifers; often reported from sandy soil (but my collections in Illinois have not been in sandy areas); summer and fall; common in the southeastern United States but not infrequent in the Great Lakes region and the northeast.

Cap: 5-11 cm; convex, expanding to planoconvex or flat; grayish brown; usually darker in the center; with small, dark streaks that radiate outwards; usually naked but occasionally featuring a whitish patch; the margin lined faintly or strongly at maturity.

Gills: Free from the stem or slightly attached to it; crowded or close; whitish; with frequent short-gills.

Stem: 5-10 cm long; up to 2 cm thick; tapering slightly to apex; whitish, sometimes discoloring a little brownish; finely hairy to shaggy; with a white, skirtlike ring that may discolor brownish; with a slightly enlarged but not bulbous base that is set in a sack-like, flaring or lobed, white volva.

Flesh: White; unchanging when sliced.

Odor: Not distinctive.

Spore Print: White.

Chemical Reactions: KOH on cap surface negative.

Microscopic Features: Spores 8.5-13.5 x 5.5-7 µ; ellipsoid; smooth; inamyloid. Basidia 4-spored; clamped. Pileipellis an ixocutis of hyphae 2-7 µ wide. Lamellar trama bilateral; subhymenium ramose.

REFERENCES: (Peck, 1880) Saccardo, 1887. (Kauffman, 1918; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Jenkins, 1986; Phillips, 1991/2005; Lincoff, 1992; Horn, Kay & Abel, 1993.) Herb. Kuo 08260502, 07090703.

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Spores

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Kuo, M. (2013, May). Amanita spreta. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_spreta.html