Amanita muscaria var. formosa

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by Michael Kuo

This variety of Amanita muscaria is distinguished by its yellow, rather than red, cap. Its other trademark features are shared with the red version: white warts on the cap, a sturdy white ring, and a distinctive stem base that has several shaggy "zones" above a basal bulb. Though its range extends across North America, it is more commonly found in the east.

In northern Michigan Amanita muscaria var. formosa fruits in great quantities, regularly attaining dinner-plate size, while the red Amanita muscaria is rare or absent. Since it is a fairly gregarious mushroom, one often finds large troops of these mammoth Amanitas lurking under quaking aspen at the edges of fields.

Like the red variety, Amanita muscaria var. formosa is poisonous, containing ibotenic acid, which the body processes as muscimol. The effects vary from person to person, and from mushroom to mushroom, ranging from hallucinations to narcotic sleep to serious discomfort. Other toxins in Amanita muscaria have not yet been identified, but produce vomiting and nausea--sometimes enough to require hospitalization. I have seen footage of a bear eating huge quantities of Amanita muscaria, then stumbling around like a big drunkard for hours, reeling at the sky, acting like a cub, chasing things that were not there . . . then finally vomiting and sleeping for days. If the first part sounds like fun to you, I advise you to consider the last part, and change your mind.

Description:

Ecology: Mycorrhizal with hardwoods and conifers; growing alone or gregariously, sometimes in fairy rings; summer and fall; widely distributed in North America, but most common in the northeast.

Cap: 4-16 cm, convex, becoming broadly convex to flat in age; smooth underneath the warts; sticky when wet or fresh; pale yellow to orange yellow, fading with age; with many cottony white warts; the margin usually slightly lined.

Gills: Free from the stem; white; crowded.

Stem: 4-15 cm long; 1-3 cm thick; more or less equal, or frequently tapering to apex and flaring to an enlarged base; typically somewhat shaggy; white; with a persistent, whitish, skirtlike ring; with a prominent rim, and (often) concentric rim-like bands at the top of the base.

Flesh: White throughout.

Spore Print: White.

Microscopic Features: Spores 9-13 x 6-8 µ; smooth; broadly elliptical; nonamyloid.

REFERENCES: (Persoon, 1799) Saccardo, 1887. (Thiers, 1982; Arora, 1986; Jenkins, 1986; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; Roody, 2003; Tulloss, 2003; McNeil, 2006.) Herb. Kuo 09019512, 11220403, 11220406, 09150712.

According to Amanita expert Rodham Tulloss (2003), the correct name for the variant described above is Amanita muscaria var. guessowii; see the link below.

Amanita muscaria var. flavivolvata has a bright red cap; Amanita muscaria var. alba has a white cap.

Further Online Information:

Amanita muscaria var. guessowii at Tulloss's Studies in Amanita
Amanita muscaria var. formosa at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2002, September). Amanita muscaria var. formosa. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_muscaria_formosa.html