Boletus pseudosensibilis

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

by Michael Kuo

A number of species are very close in appearance to Boletus pseudosensibilis--all with reddish brown to brown caps, yellow flesh and pore surfaces that bruise blue, and non-reticulate yellowish stems with varying degrees of reddish colorations. Among these mushrooms, however, Boletus pseudosensibilis is apparently the only one that displays a blue flash when a drop of ammonia is applied to the cap. Additionally, Boletus pseudosensibilis has somewhat shorter spores than most of its look-alikes, and it tends to have less red on the stem than some of the others.

Description:

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

Cap: 6-14 cm; convex, becoming broadly convex or almost flat; dry; smooth; in age becoming somewhat cracked, with yellow flesh showing through the cracks; reddish brown to yellowish brown; margin even.

Pore Surface: Bright yellow; not bruising or bruising faintly when young--later bruising blue, then brown; 1-3 pores per mm at maturity; tubes 5-8 mm deep.

Stem: 8-16 cm long; 1.5-3 cm thick; more or less equal, or enlarging to base; dry; solid; yellow overall, with reddish tinges toward the base; not reticulate.

Flesh: Whitish to pale yellow in the cap; deep yellow or red in the stem; staining quickly blue on exposure.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia flashing blue, then resolving to purplish gray on cap surface; negative to grayish on flesh. KOH yellow to orange on cap surface; brownish to orangish on flesh. Iron salts grayish on cap; grayish olive on flesh.

Spore Print: Olive brown.

Microscopic Features: Spores 9-12 x 3-4 µ; smooth; subfusoid.

REFERENCES: Smith & Thiers, 1971. (Smith & Thiers, 1971; Smith, Smith & Weber, 1981; Phillips, 1991/2005; Both, 1993; Bessette, Roody & Bessette, 2000; Roody, 2003.) Herb. Kuo 07250304, 08210501, 08180601, 07300701.

Further Online Information:

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

Click the image below for a movie of the cap's reaction to ammonia.

(WMV file - 410KB)

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Cite this page as:

Kuo, M. (2004, January). Boletus pseudosensibilis. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_pseudosensibilis.html