Amanita cokeri

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by Michael Kuo

I doubt I have found a more beautiful mushroom than this one. Amanita cokeri takes my breath away every time I find it--which, unfortunately, is not often.

Field guides feature Amanita cokeri fairly regularly, but always warn the reader that many look-alikes exist, and that positive identification is therefore unlikely. While this is true in a general sense (there are over 40 white Amanita species, most of which have white warts), I don't think the endeavor is impossible or futile; in fact, with careful observation of macrofeatures one can narrow the possibilities down pretty substantially--and with the simplest of microscopic analyses (measuring spores), one can reach a fair level of identification confidence with many of these mushrooms.

Amanita cokeri is actually pretty distinctive among the "Lepidellas" and other white amanitas. As is usually the case with Amanita species, a close look at the stem base is the starting point. Amanita cokeri has a fairly thick basal bulb that extends a shallow "root" into the ground (if the root is very long, however, you have found something else). At the top of the bulb and on the lower portion of the stem, there are more or less concentric bands of large, peeled-back scales (true scales, rather than zones of felty or shaggy material as in Amanita muscaria, which has white forms--see the illustrations on the Amanita muscaria var. formosa page for examples of felty/shaggy zones).

Aside from the stem base, distinctive features of Amanita cokeri include the cap scales, which are large and pointy and become brownish; the amyloid spores; the very thick ring, which is often double-edged, lined on the top, and shaggy below (note that the right-hand specimen in the fourth illustration is obviously going to produce a double ring, since one ring is already hanging on the stem while the partial veil still covers the gills); and the rather large size of the spores (measurements below).

Though it is one of the most beautiful mushrooms on the planet, Amanita cokeri is for admiration and study only; do not eat these or any other amanitas!

Description:

Ecology: Mycorrhizal with hardwoods or conifers; summer and fall; distribution centered in the southeastern United States, but also known from Idaho and Illinois.

Cap: 7-15 cm; oval or convex, expanding to convex or planoconvex; dry or sticky when wet; white; covered with fairly large, pointed, white to brownish warts; the margin not lined.

Gills: Free from the stem or slightly attached to it; close or crowded; white to cream; with frequent short-gills (see third illustation).

Stem: 10-20 cm long; 1-2 cm thick; tapering slightly to apex; white; smooth above or somewhat shaggy; with a fairly large basal bulb that is shallowly "rooted"; with more or less concentric zones of distinctive, down-turned scales on the upper bulb and lower stem (see second and fourth illustrations); with a thick, persisting ring that is often double or double-edged (or often lined on the upper side and tissuelike to shaggy beneath).

Flesh: White; not staining on exposure.

Odor: Not distinctive.

Chemical Reactions: KOH on cap surface negative.

Spore Print: White.

Microscopic Features: Spores 11-14 x 6-9 µ; elliptical; smooth; amyloid.

REFERENCES: (Gilbert & Kuhner, 1928) Gilbert, 1941. (Smith, Smith & Weber, 1979; Weber & Smith, 1985; Jenkins, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Roody, 2003; Miller & Miller, 2006.) Herb. Kuo 07129701, 07280301, 06290706.

In the northeastern United States a very similar, as yet unnamed species grows under conifers and in mixed woods. It has "distinctive odor of cedar closet mixed with burnt sugar," a tendency to stain pinkish or reddish, and narrower spores (Tulloss, 2003, pers. com.).

Further Online Information:

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

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Cite this page as:

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