Boletus frostii

[ Basidiomycetes > Boletales > Boletaceae > Boletus . . . ]

by Michael Kuo

The sticky red cap of this fairly unmistakable bolete is red--like, the primary color red--rather than the "red" of so many Boletus species that are actually brownish red or rusty red (and so on). Other distinguishing features for Boletus frostii include its red pore surface; its deeply and coarsely reticulate stem; and the fact that its pore surface and flesh bruise promptly blue. Boletus frostii is a mycorrhizal associate with hardwoods--especially oaks--in eastern North America, pockets of the Southwest, Mexico, and Central America.

Boletus frostii is edible, but I do not recommend experimenting with it. Although it is sold in Mexican markets, it apparently affects some people negatively--and beginners might confuse it with several poisonous red-pored species. The safest course for "boletivores" (David Arora's term for fans of edible boletes) is to avoid all red-pored, blue-bruising species.

Description:

Ecology: Mycorrhizal with oaks and other hardwoods; growing alone, scattered, or gregariously; summer and fall; widely distributed in eastern North America, Texas, pockets of the Southwest, Mexico, and Central America.

Cap: 5-15 cm, convex to broadly convex in age; sticky or thinly slimy when fresh; smooth or very finely and shallowly pock-marked; bright red, developing yellowish areas with age.

Pore Surface: Dark to pale red; bruising promptly dark blue; often exuding yellowish droplets when young; 2-3 pores per mm; tubes yellowish to olive, to 15 mm deep.

Stem: 4-12 cm long; up to 3.5 cm thick; more or less equal; coarsely and prominently reticulate over the entire length; red, or occasionally with yellow areas; often bruising blue.

Flesh: Whitish to yellow; bluing when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH black or grayish, then orangish on cap surface; grayish orange on flesh. Ammonia negative on cap; grayish or yellowish on flesh. Iron salts negative or yellowish on cap and flesh.

Spore Print: Olive brown.

Microscopic Features: Spores 11-15 (-18) x 4-5 µ; smooth; subfusiform. Pileipellis a tangled layer of gelatinized hyphae 3-6 µ wide.

REFERENCES: Russell (in Frost), 1874. (Saccardo, 1891; Coker & Beers, 1943; Singer, 1947; Snell & Dick, 1970; Smith & Thiers, 1971; Smith, Smith & Weber, 1981; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Both, 1993; Bessette, Roody & Bessette, 2000; Roody, 2003; Miller & Miller, 2006.) Herb. Kuo 08160601.

Further Online Information:

Boletus frostii in Smith & Thiers, 1971
Boletus frostii at Macrofungi of Costa Rica
Boletus frostii at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2007, January). Boletus frostii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_frostii.html