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Tricholoma species 01: "pseudofulvum"

[ Basidiomycota > Agaricales > Tricholomataceae > Tricholoma . . . ]

by Michael Kuo

I find this Tricholoma species under oaks in the Midwest, in summer and fall. It has an orangish brown to reddish brown cap, pale yellow gills that eventually spot and discolor rusty brown, and a strong, mealy odor. Its cap turns brownish red with a drop of KOH.

I identified this mushroom previously as "Tricholoma fulvum," both here and in Mushrooms of the Midwest (Kuo & Methven 2014), but I am now convinced by Christensen and Heilmann-Clausen (2013) that Tricholoma fulvum is a circumboreal species associated almost exclusively with birches. The mushroom described here is a reasonable match, morphologically, for Tricholoma fulvum, but it is mycorrhizal with oaks in the temperate zone (additionally, the red KOH reaction is not described for Tricholoma fulvum). I suspect the mushroom described here may be an unnamed species.

Peck's Tricholoma transmutans, originally described from New York in 1878, may represent the same mushroom I am describing here. Peck said the species occurred on the "[g]round in woods," without specifying trees. His brief description, which calls the gills "whitish or pale yellow," is a plausible match for the mushroom described here—but recent authors (Bessette and collaborators 2013) have used the name transmutans to apply to a conifer-associated species with buff, rather than yellow, gills.


Ecology: Mycorrhizal with oaks; growing alone, scattered, or gregariously; summer and fall; distribution uncertain. The illustrated and described collections are from Illinois and Kentucky.

Cap: 3.5–7 cm; convex, becoming broadly convex when mature; tacky when fresh but soon dry; bald; orangish brown to reddish brown, fading to orangish tan; often becoming minutely pocked or pitted with age; the margin at first inrolled.

Gills: Attached to the stem by a notch; close; short-gills frequent; pale yellow; discoloring and spotting rusty brown with age.

Stem: 3–7 cm long; 1–2 cm thick; more or less equal; bald or finely silky; often with a white zone at the extreme apex, but brownish elsewhere; hollowing; basal mycelium pastel yellow.

Flesh: White to yellowish in the cap; yellowish to yellow in the stem; unchanging when sliced.

Odor and Taste: Strongly mealy.

Chemical Reactions: KOH brownish red on cap surface.

Spore Print: White.

Microscopic Features: Spores 5–7 x 3.5–5 µm; ellipsoid; smooth; inamyloid; hyaline and uniguttulate in KOH. Basidia 4-sterigmate. Pleurocystidia not found. Cheilocystidia not found. Pileipellis a cutis of cylindric elements 3–10 µm wide, smooth or finely encrusted, reddish brown en masse in KOH. Clamp connections not found.

REFERENCES: (Peck, 1878; Kauffman, 1918; Ovrebo, 1980; Bessette et al., 2013; Christensen & Heilmann-Clausen, 2013; Kuo & Methven, 2014.) Herb. Kuo: 07270706, 09240802, 09241108, 09011606.

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Tricholoma species 01

Tricholoma species 01

Tricholoma species 01

Tricholoma species 01

Tricholoma species 01

Tricholoma species 01

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Kuo, M. (2019, September). Tricholoma species 01: "pseudofulvum." Retrieved from the MushroomExpert.Com Web site: