Description from the personal notebook of L.R. Helser provided by TENN.
AMANITA ABRUPTA Pk.
Torrey Bot. Club Bul, 24:138. 1897.
Pileus 6-10 cm. broad, hemispherical at first, convex-expanding, white, shining, dry, covered with rather sharp, pyramidal, pale straw-colored to whitish warts (2-3 mm. high) often arranged in concentric rings, easily separable and finally washed away, margin even or short striate in age. Context white, soft, thick on disk, thin on margin; odor and taste mild.
Lamellae free, with an adnate-decurrent line, moderately close to crowded, usually broad (10 mm.) in front, narrow behind, white becoming ivory yellow; edges entire.
Stipe 8-11 cm. long, 6-18 mm. thick, tapering slightly upward, white, dry, soft-spongy, with a distinct cylinder, glabrous, solid, bulbous (3.5-4 cm. diam.), the bulb abrupt, often flattened above, subglobose, rounded below, not radicate. Annulus superior, membranous, persistent, white, the lower surface attached to stipe by fibers. Volva usually a zone of remnants along the margin of the bulb, and at times on the stipe-base.
Spores 7-10 x 6-8 microns, ellipsoidal or subglobose, smooth, amyloid.
Habit, habitat, and distribution. - On soil, in conifer and deciduous woods, Tennessee, North Carolina, and Alabama, July-September.
Observations. - Murrill's A. abrubtiformis is distinguished by flat volval patches on the pileus, fibrillose stipe, and oblong spores.
The type: spore (7) 8-10 x (5.5) 6.5-7-5 microns, ellipsoid, amyloid.