Boletus hortonii

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by Michael Kuo

This mushroom is sort of a thick, wrinkled version of Boletus subglabripes. In fact, it was previously known as a variety of that species, until it was elevated to species status by Smith & Thiers (1971). It is found in the northeastern United States and in eastern Canada, and can be recognized by its wrinkled, reddish brown to brown cap, its yellowish pore surface that does not bruise (usually; see below), its yellowish, non-reticulate stem, and its mild taste. A drop of ammonia on the cap confirms identification, producing a blue-green flash before resolving to olive brown.

Boletus hortonii is edible, but does occasionally stain blue, like Boletus subglabripes; beginners should avoid all blue stainers.

Description:

Ecology: Mycorrhizal with hardwoods; growing alone or scattered; summer and fall; northeastern United States and eastern Canada.

Cap: 4-14 cm; convex, becoming broadly convex; dry or sticky; conspicuously wrinkled; margin even; reddish brown to cinnamon or merely brown; fading in age.

Pore Surface: Yellow, becoming dull yellow or olive; not typically bruising, but sometimes bruising slowly blue; 2-3 pores per mm; tubes 5-10 mm deep.

Stem: 6-10 cm long; 1-2 cm thick; more or less equal, or enlarging to base; dry; solid; pale yellow to tan, sometimes flushed reddish.

Flesh: White; not typically staining on exposure, but sometimes bluing slowly and weakly.

Odor and Taste: Not distinctive.

Chemical Reactions: Cap with a blue-green flash, then olive brown with ammonia; olive brown with KOH; pale olive with iron salts. Flesh negative with ammonia; negative with KOH; bluish gray with iron salts.

Spore Print: Olive brown.

Microscopic Features: Spores 12-15 x 3.5-4.5 µ; smooth; subfusiform.

REFERENCES: Smith & Thiers, 1971. (Smith & Thiers, 1971; Smith, Smith & Weber, 1981; Phillips, 1991/2005; Both, 1993; Bessette, Roody & Bessette, 2000; Roody, 2003; McNeil, 2006; Kuo, 2007.) Herb. Kuo 05300407.

Further Online Information:

Boletus hortonii in Smith & Thiers, 1971
Boletus hortonii at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2003, February). Boletus hortonii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_hortonii.html