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--in the Lepidella section of the genus and elsewhere (see comments below).

I hope it goes without saying: Do not eat these or any other amanitas!

Description:

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; .5-1.5 cm thick; tapering slightly to apex; white; smooth or somewhat shaggy; with a prominent, large, abrupt basal bulb that is sometimes "chiseled"; with 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); often with white fibers connecting the ring and the stem.

Flesh: White; not staining on exposure.

Odor: Not distinctive.

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

Spore Print: White.

Microscopic Features: Spores 6.5-9.5 x 5.5-8.5 µ; round or broadly elliptical; smooth; amyloid.

REFERENCES: Peck, 1897. (Sacardo, 1899; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Jenkins, 1986; Phillips, 1991/2005; Metzler & Metzler, 1992; Tulloss, 2003; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 07290302, 07070704.

There is a veritable plethora of look-alikes. Amanita bulbs do not always manifest themselves as they are "supposed to," and it is very possible that the bulb of an Amanita abrupta specimen could be less distinctive than the bulbs in the illustrations. In this case, the fact that the spores are amyloid, coupled with their size, will help to eliminate many (though certainly not all) of the possibilities.

Further Online Information:

Amanita abrupta at Tulloss's Studies in Amanita
Amanita abrupta at Roger's Mushrooms

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2003, August). Amanita abrupta. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_abrupta.html