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Boletus edulis var. grandedulis

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

by Michael Kuo

California boasts several impressive members of the North American Boletus edulis group, including this stately mushroom, which grows under pines--especially Bishop pines along the coast in fall and winter, but also under other pines and firs in inland ecosystems. Boletus edulis var. grandedulis was recently named (Arora, 2008), as a particularly large variety of the European Boletus edulis that develops a dull brown to cinnamon (rather than greenish yellow) pore surface at maturity.


Ecology: Mycorrhizal with conifers, especially Bishop pine and other coastal pines, but also with pines and firs at higher elevations (rarely with coast live oak); growing alone or gregariously; fall and winter in coastal areas; summer and fall at higher elevations; central and northern California.

Cap: 10-50 cm; convex in the button stage, becoming broadly convex; tacky when wet; bald; light brown to brown, reddish brown, or yellow-brown.

Pore Surface: Whitish at first, becoming yellowish to tan and, eventually, dull brown to cinnamon; not bruising; pores "stuffed" at first but at maturity angular to circular, 2-3 per mm; tubes to about 3 cm deep.

Stem: 7-40 cm long; 3-15 cm thick; club-shaped and swollen, becoming club-shaped or more or less equal; finely reticulate over at least the upper half; white, sometimes becoming brownish.

Flesh: White; solid; unchanging when sliced.

Odor and Taste: Pleasant, but not distinctive.

Chemical Reactions: Ammonia on flesh red to pink. KOH on flesh brownish.

Spore Print: Olive brown.

Microscopic Features: Spores 13-15.5 x 4-5.5 µ; smooth; fusiform.

REFERENCES: Arora, 2008. (Thiers, 1975; Arora, 1986; Arora, 2008.)

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


Boletus edulis var grandedulis

Boletus edulis var grandedulis

Boletus edulis var grandedulis

Boletus edulis var grandedulis

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