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2012-02-11T22:22:18Z

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Amanita rubescens

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

by Michael Kuo

This beautiful amanita is widely distributed and common in eastern North America. It can be distinguished by its indistinct stem base (which lacks a prominent sacklike covering or rim), its dull yellowish to dull brownish cap, and its tendency to discolor pinkish red to rose; it is sometimes called the "Blusher." Another common "blushing" Amanita species in the east, Amanita flavorubescens, has yellow, rather than grayish, warts and volva remnants (as well as a brighter yellow cap surface). Amanita rubescens var. alba has a whitish cap. The western version of Amanita rubescens is Amanita novinupta.

Strictly speaking, the "Amanita rubescens" of North American authors may not be the same mushroom as the "true" Amanita rubescens, from Europe. Amanita expert Rod Tulloss has identified at least a dozen distinct blushers world-wide (see Tulloss's key to these amanitas), and notes that the mushroom labeled Amanita rubescens on our continent differs in several macro- and microscopic features.

To see what happens when Amanita rubescens is attacked by aliens from outer space, see Hypomyces hyalinus.

Description:

Ecology: Mycorrhizal with conifers and hardwoods, but especially fond of oaks; throughout summer and fall; probably limited to eastern North America (see comments below).

Cap: 4-12 cm; convex to broadly convex or flat in age; dry or slightly sticky; with yellow warts when young, but the warts soon fading to pinkish, grayish or dull tan; surface pale to brownish when young, becoming flushed with red shades, and eventually reddish brown to tan to brown; margin typically not lined.

Gills: Attached or free from the stem; white, sometimes discoloring reddish; close.

Stem: 5-14 cm long; 1.5-3 cm thick; more or less equal, sometimes slightly enlarged toward base; the base indistinct to bulbous; generally without volval remnants (but perhaps with indistinct volval scales or zones); without a rim; white becoming stained pinkish to dirty red; smooth to finely hairy; with a fragile superior ring that typically persists into maturity.

Flesh: White throughout, discoloring slowly pale pinkish red, especially around worm holes.

Spore Print: White.

Chemical Reactions: KOH on cap surface negative.

Microscopic Features: Spores 7.5-10.5 x 5-7µ; smooth; elliptical; amyloid.

REFERENCES: Persoon, 1797. (Fries, 1821; Saccardo, 1887; Kauffman, 1918; Smith, 1949; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Arora, 1986, Jenkins, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Tulloss & Lindgren, 1994; Tulloss et al., 1995; Barron, 1999; Roody, 2003; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 06239502, 08300211, 07070711.

Further Online Information:

Amanita rubescens at Tulloss's Studies in Amanita
Amanita rubescens at Roger's Mushrooms
Amanita rubescens at Fungi of Poland[http://www.mushroomexpert.com/images/nadon/nadon_amanita_rubescens_thumb.jpg]

Amanita rubescens - Revision history

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