Pluteus thomsonii

[ Basidiomycetes > Agaricales > Pluteaceae > Pluteus . . . ]

by Michael Kuo

Field guides (for example, Roody, 2003) describe and illustrate a distinctive mushroom with a prominently veined cap as Pluteus thomsonii. I have never found specimens with such prominent veins over the center of the cap, but I have found many like the ones illustrated here, which match Pluteus thomsonii in all other respects. And, according to Pluteus expert Richard Homola (1972), "the extent of the reticulate venations of the pileus varies considerably in P. thomsonii. In larger specimens the venation is very prominent and conspicuous and in smaller, mature specimens it may be absent" (1220).

As I have collected it in Wisconsin and Illinois, Pluteus thomsonii is sort of a miniature version of Pluteus cervinus. Hmmm . . . a miniature version of a throughly boring brown mushroom. No wonder Alexander Smith (1979) calls this species "not rare but seldom collected." But lovers of LBMs (Little Brown Mushrooms) will have a field day with Pluteus thomsonii; its "distinctive" macrofeatures barely separate it from other small Pluteus species--and a microscope is required for certain identification.

So, for the true believers and the forever faithful, here goes: Pluteus thomsonii is distinguished by its diminutive size, its relatively dark brown cap, and by its cystidia (special sterile cells on the gill faces), which lack horn-like projections and measure 39-61 x 8-18 µ.

I have no information on the edibility of Pluteus thomsonii. It is too small and insubstantial to consider for the table, anyway.

Description:

Ecology: Saprobic on decaying hardwood logs and debris; growing alone or gregariously; summer and fall; widely distributed east of the Rocky Mountains.

Cap: 1-3.5 cm; convex becoming broadly convex with a central bump; blackish brown, fading to dull brown; smooth overall but with a wrinkled or veined center.

Gills: Free from the stem; close or nearly distant; whitish or grayish at first, becoming pinkish.

Stem: 2-4.5 cm long; 1.5-6 mm thick; equal; silky-streaked; pale.

Flesh: Insubstantial; pale.

Odor and Taste: Not distinctive, or slightly radishlike to bleachlike.

Spore Print: Pink.

Microscopic Features: Spores 6-8 x 5.5-6 µ; elliptical; smooth. Cystidia 39-61 x 8-18 µ; without horn-like projections.

REFERENCES: (Berkeley & Broome, 1876) Dennis, 1948. (Saccardo, 1887; Homola, 1972; Smith, Smith & Weber, 1979; Roody, 2003.) Herb. Kuo 07100304, 07290303, 10160301.

"Pluteus thompsonii" (with a P) is a misspelling propagated by a typo in Smith, Smith & Weber (1979).

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Cite this page as:

Kuo, M. (2004, December). Pluteus thomsonii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/pluteus_thomsonii.html