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Boletus pallidus

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

by Michael Kuo

Does the pore surface bruise blue? Maybe, maybe not. Does the flesh turn bluish on exposure? Maybe, maybe not--or maybe it feels like turning pinkish. Don't mushrooms read the field guides and monographs to find out what they're supposed to do?!

Don't rely heavily on color changes from bruising or exposure to air for your identification decisions with this mushroom (within reason; if your mushroom instantly changes to blackish blue when you slice it open, it's definitely not Boletus pallidus). Look for the pale cap, smooth white stem, yellowish to olive pore surface, and the olive to olive brown (not yellow brown) spore print.

The similar Boletus alutaceus is somewhat smaller, never bruises or stains blue, has a lighter spore print, fatter spores, and often has a yellowish stem base.


Ecology: Mycorrhizal with hardwoods, especially oaks; growing alone, gregariously, or in small clumps; summer and fall; widely distributed in eastern North America.

Cap: 4-15 cm; convex, becoming broadly convex or nearly flat in age; dry; smooth or very finely velvety; sometimes becoming finely cracked in age; the margin often with a tiny overhanging sterile portion; whitish to buff or pale tan, sometimes developing rose shades.

Pore Surface: Whitish to yellowish when young, becoming yellow to greenish yellow; bruising bluish, then brownish--or not bruising; pores circular, becoming angular, 1-2 per mm; tubes to 2 cm deep.

Stem: 5-12 cm long; 1-2.5 cm thick; more or less equal; white; sometimes yellowish at apex, sometimes with pale reddish colors below in age (but not as strikingly or consistently red as the stem of Boletus inedulis); sometimes developing brownish streaks; not reticulate; basal mycelium white.

Flesh: Whitish to pale yellow; typically staining slowly and erratically pale blue on exposure, especially above the tubes--but often not staining, or staining pinkish.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia negative to orangish on cap surface; greenish on flesh. KOH rusty orange on cap surface; orangish on flesh. Iron salts negative to orangish on cap surface; negative to orangish on flesh.

Spore Print: Olive to olive brown.

Microscopic Features: Spores 9-15 x 3-5 µ; smooth subfusoid.

REFERENCES: Frost, 1874. (Saccardo, 1891; Coker & Beers, 1943; Singer, 1947; Snell & Dick, 1970; Smith & Thiers, 1971; Smith, Smith & Weber, 1981; Phillips, 1991/2005; Both, 1993; Barron, 1999; Bessette, Roody & Bessette, 2000; Roody, 2003; McNeil, 2006; Miller & Miller, 2006; Kuo, 2007; Ortiz-Santana et al., 2007; Binion et al., 2008.) Herb. Kuo 07319701, 09050202, 08160604, 09150717.

This site contains no information about the edibility or toxicity of mushrooms.


Boletus pallidus

Boletus pallidus

Boletus pallidus

Boletus pallidus

Boletus pallidus

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Kuo, M. (2002, September). Boletus pallidus. Retrieved from the MushroomExpert.Com Web site: