Tricholoma scalpturatum
Mém. Soc. Émul. Montbéliard, Sér. 2. 5: 232. 1872.
Common Name: none
Basionym: Agaricus scalpturatum Fr.
Cap 30-70 mm broad, convex, expanding to plano-convex or plane; margin at first, incurved, becoming decurved, occasionally wavy, upturned in age; surface dry, blackish-brown, fibrillose-squamulose at disc, paler towards the margin with greyish brown appressed fibrils and scales; context white, greyish beneath the cuticle, soft, unchanging, 5-7 mm in thickness near stipe; odor and taste strongly of cucumber.
Gills crowded, maturing close, sinuate, ash-grey to nearly white in age, sporadically tawny-yellowish in old specimens; relatively broad, 7 (9) mm in width, edges even; lamellulae in 2-3 series.
Stipe 20-60 x 10-20 (25) mm broad, cylindrical, straight, solid to hollow in age, equal to enlarged at apex; surface white unchanging, with a covering of appressed fibrils, scattered rhizomorphs at base; partial veil grey, fibrillose, best seen when immature, leaving an evanescent zone of fibrils high on stipe.
Spores 4.5-6.0 (6.5) x 3.0-4.0 microns, ellipsoid, smooth, hilar appendage small but distinct; spores inamyloid, white in deposit.
Solitary to clustered in mixed conifer-hardwood forests; especially common with coast liveoak (Quercus agrifolia) in the San Francisco Bay Area; fruiting from fall to mid-winter; common.
Unknown.
Tricholoma scalpturatum is a small to medium-sized species recognized by a sooty, black, fibrillose-squamulose cap disc, paler toward the margin with greyish brown fibrils and scales. Tricholoma scalpturatum is common, sometimes abundant under coast liveoak (Quercus agrifolia). Its strong farinaceous odor, though not definitive, is a helpful identifying character, as is its occurrence under oaks. A look-alike, Tricholoma terreum var. cystidiotum tends to occur more under conifers, especially pines (Pinus spp.) in the San Francisco Bay Area. It differs in a more uniformly greyish-black, fibrillose cap, lacks the farinaceous odor of T. scalpturatum, and microscopically has a hypodermium of inflated cells. Other small greyish Tricholomas include T. cingulatum, an uncommon greyish, fibrillose cap species that occurs with willow (Salix spp.). It is distinguished by a well-developed white cottony ring. A final member of the small, greyish clan is Tricholoma moseri. It is a montane species found under conifers most commonly in spring near melting snowbanks. Besides habitat and fruiting pattern it is best identified microscopically by spore size, up to 10µm in length, larger than any of the above species.
The taxonomic status of this European named species is uncertain. A DNA study of European specimens indicates that Tricholoma scalpturatum is a species complex harboring several closely related taxa. Further research and data is need to clarify the identity our California species.
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Shanks, Kris M. (1997). The Agaricales (Gilled Fungi) of California. 11. Tricholomataceae II. Tricholoma. Mad River Press: Eureka, CA. 54 p.
scalpturatum