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Boletus cf. edulis

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

by Michael Kuo

No, "cf" doesn't stand for "chicken fried," even though I am writing this in the Midwest (where, for the uninitiated, we actually have a popular meal called "chicken fried steak"). It's a mycological convention that abbreviates a Latin verb for "compare" (conferre)--as in, "compare this mushroom to Boletus edulis." In other words, "cf" is what mycologists say when they don't want to actually say, "I dunno; maybe."

Maybe it's Boletus edulis, the well known European species. Like the European mushroom, our eastern North American version has a tacky, bald cap--and, like the European species, it is usually found under spruces, though it is occasionally found under other conifers or even hardwoods. The cap color, however, is consistently what I would call "orangish brown" or "cinnamon," while the European species is simply brown. For examples of the color difference, compare the photos and drawings here and on the Boletus edulis page--and compare European and North American photos on Roger Phillips's page for the species (North American collections have blue backgrounds; European collections have gray backgrounds).

A throng of roughly similar North American species constitutes the North American Boletus edulis group, but most are fairly easily separated from the mushroom described here on the basis of geography and/or physical features.


Ecology: Mycorrhizal with conifers, especially spruces, and (rarely) with hardwoods; growing alone, scattered, or gregariously; summer and fall; distribution uncertain, but possibly limited to northeastern North America. In my area (central Illinois), I have never found the mushroom I am describing here; I have seen it only in Pennsylvania and in northern Michigan. The illustrated mushrooms are from Pennsylvania and Quebec.

Cap: 8-25 cm, convex in the button stage, becoming broadly convex to nearly flat; greasy to tacky, or sticky when wet; bald; light to dark orangish brown (oac 644, oac 650).

Pore Surface: Whitish at first, becoming yellowish and eventually olive yellow; not bruising; pores "stuffed" when young; at maturity with 2-3 round pores per mm; tubes to 3 cm deep.

Stem: 10-18 cm long; 2-4 cm thick; usually swollen and club-shaped when young, becoming club-shaped to more or less equal; finely reticulate over at least the upper portion; white, or with brownish areas.

Flesh: White; firm; unchanging when sliced; sometimes tinged with rose shades near the cap surface and around worm holes.

Odor and Taste: Pleasant, but not distinctive.

Chemical Reactions: KOH negative to brownish on flesh.

Spore Print: Olive brown.

Microscopic Features: Spores 13-19 x 4-6.5 µ; smooth; subfusiform.

REFERENCES: (Coker & Beers, 1943; Snell & Dick, 1970; Smith & Thiers, 1971; Grund & Harrison, 1976; Smith, Smith & Weber, 1981; Phillips, 1991/2005; Lincoff, 1992; Both, 1993; Barron, 1999; Roody, 2003; McNeil, 2006; Miller & Miller, 2006; Kuo, 2007.)

Further Online Information:

Boletus edulis var. edulis in Smith & Thiers, 1971
Boletus edulis at Tom Volk's Fungi
Boletus edulis at Roger's Mushrooms


Boletus cf. edulis

Boletus cf. edulis

Boletus cf. edulis

Boletus cf. edulis

Boletus cf. edulis

Boletus cf. edulis

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Kuo, M. (2010, March). Boletus cf. edulis. Retrieved from the MushroomExpert.Com Web site: