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Boletus auripes

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

by Michael Kuo

Boletus auripes is found east of the Rocky Mountains in hardwood forests; it is especially fond of oaks. When fresh, it has a striking yellow stem that contrasts nicely with its brown cap. Other defining features include the fine reticulation on the stem surface, the absence of any blue bruising or staining, and the yellow pore surface that becomes olive yellow with maturity.


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

Cap: 6-20 cm; convex, becoming broadly convex; dry; finely velvety or nearly smooth; yellow-brown or golden when in the button stage, becoming brown or yellowish brown, eventually fading.

Pore Surface: Bright to medium yellow, becoming brownish yellow or olive; not bruising; 2-3 pores per mm; tubes to 2 cm deep.

Stem: 5-12 cm long; up to 3 cm thick; more or less equal, or with a swollen bottom half (especially when young); usually finely reticulate over at least the top portion; bright yellow becoming brownish yellow; often discoloring brownish with age.

Flesh: Yellow; not staining on exposure, but sometimes becoming deeper yellow. According to Both (1993), collections made in New York sometimes demonstrate faint bluing when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia yellowish or negative on cap and flesh; KOH negative or yellowish on cap and flesh; iron salts negative on cap and flesh.

Spore Print: Yellow-brown, sometimes with an olive tinge in a fresh print.

Microscopic Features: Spores 9.5-15 x 3.5-5 µ; smooth; subfusiform.

REFERENCES: Peck, 1897. (Saccardo, 1899; Coker & Beers, 1943; Singer, 1947; Snell & Dick, 1970; Phillips, 1991/2005; Both, 1993; Bessette, Roody & Bessette, 2000; Roody, 2003; Ortiz-Santana et al., 2007.) Herb. Kuo 06279503, 08260503.

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


Boletus auripes

Boletus auripes

Boletus auripes

Boletus auripes

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Kuo, M. (2007, January). Boletus auripes. Retrieved from the MushroomExpert.Com Web site: