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Amanita abrupta

[ Basidiomycetes > Agaricales > Amanitaceae > Amanita . . . ]

by Michael Kuo

White amanitas with warts are not among the easiest mushrooms to identify, but Amanita abrupta has a very distinctive stem base, making it more recognizable than many others.

"Abrupt" is a perfect description of the basal bulb of Amanita abrupta; it looks like an egg that has been sliced off and stuck on the end of the stem! The top of the bulb does not have a rolled-over rim, nor does it have concentric zones of shagginess or scales. If this seems like an awful lot of emphasis on one part of the mushroom, remember that without its bulb, Amanita abrupta would join the ranks of the many seemingly indistinguishable white Amanita species.


Ecology: Mycorrhizal with hardwoods or conifers; summer and fall; widely distributed in eastern North America.

Cap: 4-10 cm; convex, expanding to planoconvex or flat; dry; white; covered with small to large, conical, white to off-white warts that are randomly distributed, but smaller and denser near the margin; the margin not lined.

Gills: Free from the stem or slightly attached to it; crowded, close, or nearly distant; white to cream, sometimes with a pale orange cast; with frequent short-gills.

Stem: 6-12 cm long; 0.5-1.5 cm thick; tapering slightly to apex; white; bald or somewhat shaggy; with a prominent, large, abrupt basal bulb that is sometimes "chiseled" and often features white mycelial threads on the bottom; with a thick, persisting ring that may be double or double-edged (or often lined on the upper side and tissuelike beneath).

Flesh: White; not staining on exposure.

Odor: Not distinctive when young, becoming unpleasant (like meat that is beginning to rot) with age.

Chemical Reactions: KOH on cap surface negative to slightly pinkish.

Spore Print: White.

Microscopic Features: Spores 6.5-9.5 x 5.5-8.5 µ; subglobose or broadly ellipsoid; smooth; amyloid. Basidia 4-spored; basally clamped. Pileipellis a slightly gelatinized cutis of elements 3-8 µ wide. Lamellar trama bilateral; subhymenium with inflated cells.

REFERENCES: Peck, 1897. (Saccardo, 1899; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Jenkins, 1986; Phillips, 1991/2005; Metzler & Metzler, 1992; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 07290302, 07070704, 07190804.

This site contains no information about the edibility or toxicity of mushrooms.


Amanita abrupta

Amanita abrupta

Amanita abrupta

Amanita abrupta

Amanita abrupta

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Kuo, M. (2013, March). Amanita abrupta. Retrieved from the MushroomExpert.Com Web site: