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Amanita muscaria var. alba

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

by Michael Kuo

I have collected this white variety of Amanita muscaria only once, in 1995, in northern Michigan. Unfortunately that was long before I was documenting my collections with photographs--although I did describe and preserve the collection and can therefore verify its identity, years later, with analysis and microscopic examination. Identifying features include the same features that typify all the varieties of Amanita muscaria: the warts on the cap, the ring on the upper stem, and the concentric zones of shagginess at the top of the stem base. But the cap color in this particular variety is whitish, and the warts are whitish to tan. Additionally, the stem surface bruises yellowish, then brownish in most collections.

Description:

Ecology: Mycorrhizal with conifers and hardwoods; growing alone, scattered, or gregariously; summer and fall; widely distributed in the northern United States from Washington to New York.

Cap: 4-20 cm; convex, becoming broadly convex or nearly flat; sticky when fresh; whitish to silvery white; bald beneath numerous whitish to tan, woolly to cottony warts or patches; the margin usually becoming slightly lined.

Gills: Narrowly attached to the stem or free from it; creamy white; crowded; short-gills frequent.

Stem: 5-15 cm long; 1-2 cm thick; usually tapering to apex and flaring to an enlarged basal bulb; somewhat shaggy, especially toward the base; whitish, bruising yellowish, then brownish; with a fragile, whitish, skirtlike ring; with more or less concentric bands or rings of whitish universal veil material at the top of the bulb.

Flesh: White throughout; unchanging when sliced, or turning slightly yellowish in the stem.

Odor: Not distinctive.

Spore Print: White.

Microscopic Features: Spores 8-14 x 5-9 µ; smooth; broadly ellipsoid; inamyloid. Basidia 4-spored; basally clamped. Pileipellis an ixocutis of hyphae 3-10 µ wide. Lamellar trama bilateral; subhymenium ramose or with slightly inflated elements.

REFERENCES: Peck, 1897. (Jenkins, 1986; Phillips, 1991/2005.) Herb. Kuo 09019513.

The taxonomy of the Amanita muscaria species group will very likely change in the near future. A 2006 study by Geml and collaborators found DNA support for the idea that the color of the cap and warts in Amanita muscaria is not necessarily indicative of phylogenetic differences. The study used molecular dating techniques to hypothesize that "[t]he ancestral population of A. muscaria likely evolved in the Siberian-Beringian region and underwent fragmentation . . . The data suggest that these populations later evolved into species, expanded [sic] their range in North America and Eurasia" (225). As for the traditional morphological features separating "varieties," the researchers noted that among the species determined by DNA, "[a]ll . . . share at least two morphological varieties with other species, sugesting ancestral polymorphism in pileus and wart color pre-dating their speciations."

Further Online Information:

Amanita muscaria var. alba at Studies in the Amanitaceae
Amanita muscaria var. alba at Roger's Mushrooms

 

Amanita muscaria var alba

Amanita muscaria var alba
Spores



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Cite this page as:

Kuo, M. (2013, May). Amanita muscaria var. alba. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_muscaria_alba.html