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Amanita rubescens var. alba
[ Basidiomycetes > Agaricales > Amanitaceae > Amanita . . . ]
by Michael Kuo
This mushroom is a white, stocky variety of the well known "blushing" species, Amanita rubescens. It is found in eastern North America, often growing alongside the typical variety--but one does not find "intergrading" forms, which suggests that the two taxa are indeed distinct at some level. Western North America's Amanita novinupta is similar, but features a swollen stem base and patchlike, rather than warty, decoration on its cap.
Ecology: Mycorrhizal with conifers and hardwoods, but especially fond of oaks; early summer through fall; fairly widely distributed east of the Great Plains, but apparently absent south of (roughly) South Carolina.
Cap: 5-13 cm, convex to broadly convex or broadly bell-shaped, or nearly flat in age; dry or slightly sticky; with yellowish to creamy or grayish warts; surface white, developing pinkish or reddish shades; the margin not or only faintly lined.
Gills: Free from the stem or nearly so; white, discoloring reddish; close or crowded.
Stem: 5-14 cm long; up to 2 cm thick; with a swollen base; generally without prominent universal veil remnants (but perhaps with indistinct volval scales or zones); without a rim; white becoming stained pinkish to dirty red; bald to finely hairy; with a white (rarely yellow or yellowish), fragile, skirtlike ring.
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 7-10 x 5-7 µ; smooth; broadly ellipsoid; amyloid. Basidia 4-spored; without clamps. Pileipellis a cutis or ixocutis of hyphae 2-6 µ wide. Lamellar trama bilateral; subhymenium ramose or nearly cellular.
REFERENCES: Coker, 1917. (Saccardo XXVI ; Jenkins, 1986; Kuo & Methven, 2010; Tulloss, 2013.) Herb. Kuo 07070712.
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Cite this page as:
Kuo, M. (2013, May). Amanita rubescens var. alba. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_rubescens_alba.html