E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
{See also Tricholoma with coal tar odor Table.} Tricholoma bufonium is characterized by a reddish brown to purple brown cap, yellow flesh and gills, a yellow stem that is sometimes purple-tinted, and a coal tar odor. "Many authors place this species in the circle of forms around Tricholoma sulphureum... or consider it to be one of its varieties...We noticed that the number of lamellae in our collections of T. bufonium was about twice as large as in T. sulphureum. If this feature is constant, it would surely justify the rank of species.", (Breitenbach). Comandini(1) presents a good argument for the synonymy of this taxon with Tricholoma sulphureum on the grounds that microscopic differences are slight, color intermediates occur, and molecular techniques do not distinguish them.

There are collections from BC at the University of British Columbia and collections from WA at the University of Washington.

Cap:
3-7cm across, hemispheric when young, later convex to flat with incurved margin, slightly umbonate, margin acute and incurved for a long time; wine-red to purple brown in center, increasingly paler to cream or yellowish toward the margin; "dull when dry, appressed-squamose to radially fibrillose", (Breitenbach), 3-5(7)cm across, hemispherical when young, becoming convex to flat with incurved margin, slightly umbonate; reddish brown to purple reddish-brown; wine-red to pinkish brown in center from appressed to squamose radial fibers, paler or cream toward margin; dry, (Parker), purple violet-brown (Moser), up to 6cm across, convex; dark crimson brown right up to the margin which is only slightly more yellowish, (Courtecuisse), vinaceous brown cap center (Hansen)

Flesh:
thick in center, thin toward margin; sulphur-yellow, (Breitenbach), thick at cap center to thin at margin; sulphur yellow to pale yellow, pinkish at base of stem, (Parker)

Gills:
notched, 65-76 reaching stem, 3-5 subgills between neighboring gills, gills broad; sulfur yellow; edges smooth (Breitenbach), sinuate, close, broad; pale yellow to sulphur yellow, (Parker)

Stem:
4-8cm x 1-2cm, cylindric, sometimes slightly narrowed toward base or also club-shaped, stem solid, firm; sulphur-yellow, sometimes purplish-tinted; longitudinally fibrillose, finely floccose at top, (Breitenbach), (2)4-8cm x (0.5)1-2cm, cylindric to flexuous [wavy], sometimes slightly tapered or club-shaped toward base, firm, solid; pale to sulphur yellow, occasionally tinted purple; longitudinally fibrillose, finely floccose at top, (Parker)

Veil:
ring absent (Parker)

Odor:
repulsive, like carbide-illuminating gas, (Breitenbach), repulsive, like coal tar gas, (Parker), less strong than Tricholoma sulphureum, ?insecticide, (Courtecuisse)

Taste:
mild, somewhat unpleasant, (Breitenbach, Parker)

Microscopic spores:
spores 7.8-10.5 x 4.4-6.0 microns, broadly elliptic to amygdaliform, smooth, iodine-negative, colorless, with droplets; basidia 4-spored, 38-47 x 8-10 microns, cylindric-clavate, some with basal clamp connection; pleurocystidia and cheilocystidia not seen, marginal cells 25-30 x 2.5-3.5 microns, cylindric, sometimes flexuous [wavy]; cap cuticle of irregular hyphae 2.5-6 microns wide, occasional hyphal ends exserted, brown-pigmented; clamps on some basidia but not seen on cap cuticle, (Breitenbach), spores 8-12 x 4.5-6 microns, elliptic, smooth, inamyloid; pleurocystidia and cheilocystidia absent, (Parker)

Spore deposit:
white (Breitenbach, Parker)