Retiboletus griseus

[ Basidiomycetes > Boletales > Boletaceae > Retiboletus . . . ]

by Michael Kuo

Retiboletus griseus is gray and drab, and not the most memorable of boletes--though it is fairly common in eastern North America's oak-hickory forests, and relatively easy to identify. The stem is the most distinctive feature; it is reticulate with a yellowish to brownish pattern that darkens when the mushroom is handled, and it stains and bruises yellow when mature, especially in the lower half. It is often one of the first mycorrhizal mushrooms to appear in early summer--but it continues to fruit throughout the summer and into the fall.

Description:

Ecology: Mycorrhizal with oaks and other hardwoods; growing alone, scattered, or gregariously; early summer through fall; widely distributed east of the Rocky Mountains, and sometimes reported in the Southwest.

Cap: 5-14 cm; convex, becoming broadly convex or nearly flat; dry; with tiny, pressed-down, grayish fibers (use a hand lens) over a pale to gray or brownish gray base color; darkening with age and sometimes on handling.

Pore Surface: Whitish to dirty gray; not bruising, or bruising brown or darker gray; tubes to 2 cm deep.

Stem: 4-14.5 cm long; 1-3.5 cm thick; more or less equal; frequently (but not always) curved near the base ; whitish, staining yellow from the base upwards as it ages; prominently and widely reticulate (usually over the whole stem) with a yellowish reticulum that becomes brownish or blackish in age or when handled; solid.

Flesh: White, not staining, or staining dingy red or brownish, when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia negative on cap surface; negative to pale pinkish gray on flesh. KOH negative to olive on cap surface; negative to pinkish or orangish on flesh. Iron salts negative on cap surface; negative to bluish gray on flesh.

Spore Print: Pinkish brown to olive brown.

Microscopic Features: Spores 9-13 x 3-5 µ; smooth; subfusoid.

REFERENCES: (Frost, 1878) Binder & Bresinsky, 2002. (Saccardo, 1888; Coker & Beers, 1943; Singer, 1947; Smith & Thiers, 1971; Grund & Harrison, 1975; Smith, Smith & Weber, 1981; Weber & Smith, 1985; Phillips, 1991/2005; Metzler & Metzler, 1992; Both, 1993; Barron, 1999; Bessette, Roody & Bessette, 2000; Binder & Bresinsky, 2002; Roody, 2003; McNeil, 2006; Kuo, 2007; Ortiz-Santana et al., 2007; Binion et al., 2008.) Herb. Kuo 07079504, 06170201, 08290500, 06300706, 07190802.

Boletus griseus is a synonym, and is the name used by most field guides. For a discussion of the support for the genus Retiboletus, see the page for Retiboletus ornatipes.

Further Online Information:

Boletus griseus in Smith & Thiers, 1971
Boletus griseus at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2010, April). Retiboletus griseus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/retiboletus_griseus.html