Tricholoma pardinum
Mém. Soc. Émul. Montbéliard, Sér. 2 5: 339. 1873.
Common Name: none
Cap 50-100 (120) mm broad, convex, plano-convex to plane with or without a low umbo in age; margin incurved, maturing decurved to level; surface dry with dark grey-brown radially arranged fibrils and sqamules over a whitish background, darkest at the disc shading to a pallid margin; context white to ash-grey, unchanging, soft in age, up to 15 mm thick at disc, rapidly tapering towards margin; odor and taste farinaceous.
Gills adnexed to notched, close, becoming subdistant, relatively broad, up to 10 mm in width, occasionally forked at the disc, white to cream, edges bruising brownish; lamellulae in up to three series.
Stipe 70-120 mm x 15-25 mm in width, round, equal to clavate, solid, finely fibrillose at apex, sometimes lined from gill edges; surface whitish with scattered fibrils bruising brown over lower stipe; base often tinged brown; partial veil absent.
Spores 6-9 x 4-6.5 µm, ellipsoid, somewhat narrower in profile, smooth, hilar appendage well developed, contents granular, hyaline, inamyloid; spores white in deposit.
Solitary or in small groups in mixed hardwood-conifer coastal woods, possibly also in the Sierra Nevada (see Comments for confusion with Tricholoma venenatum; occasional.
Toxic, causing severe gastrointestinal upset.
Tricholoma pardinum is a robust species recognized by a cap that is dark grey, fibrillose-squamulose at the disc, becoming whitish near the margin. A white, often subclavate stipe and pallid gills are helpful but not infallible identifying characters. Other grey California Tricholomas include Tricholoma virgatum, also with a dry cap, but the cap is conic, and has appressed fibrils, rather than scales. Tricholoma nigrum, reported from coastal Oregon and Washington under pines and Douglas fir is similarly colored but the cap usually has appressed fibrils, if squamulose, only at the disc; Tricholoma atroviolaceum differs with an evenly colored dark grey, violaceus tinged fibrillose-squamulose cap and dark grey gills in age; Tricholoma griseoviolacum found under oaks and Tricholoma portentosum, typically with pines, can be distinguished by greyish purple viscid caps. In the coastal zone, two smaller grey Tricholomas with dry caps are found, Tricholoma terreum, synonymized here with Tricholoma myomyces var. cystidiotum and Tricholoma scalpturatum. Tricholoma terreum, a pine dwelling species, has a uniformly dark grey fibrillose squamulose cap, pallid only at the edge of the margin, and greyish, not whitish gills; Tricholoma scalpturatum, is similar to T. terreum, but is paler and grows typically under oaks. In the Sierra Nevada, a toxic look-alike of Tricholoma pardinum is T. venenatum. Similar in stature, its cap fibrils and squamules are light brown, not grey.
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