Cap 4.0-14.0 cm broad, unevenly convex, expanding to plano-convex; margin incurved, then decurved to upturned, frequently wavy; surface moist, more or less glabrous in youth, whitish when unexposed, becoming appressed-fibrillose, light-grey to greyish-brown over a pallid background, the center sometimes covered with a whitish bloom, older specimens occasionally splotched greyish-black; context white, soft in age, up to 1.0 cm thick, rapidly thinning toward the margin; odor and taste strongly of raw potatoes or cucumber.
Gills notched, close, broad, up to 1.2 cm in width, whitish in youth, dingy-buff at maturity, developing dull rusty-brown areas on the edges and faces; lamellulae in up to four series.
Stipe 5.0-13.0 cm long, 2.0-3.5 cm thick, straight, solid, enlarged to sub-bulbous at the base; surface of apex white with furfuraceous scales, appressed fibrillose below, sometimes tinged ochre, bruising vinaceous-brown; partial veil fibrillose-membranous, forming a thin, evanescent medial to superior ring.
Spores 8.5-11.0 x 4.0-6.0 µm, smooth, elliptical in both views, slightly inequilateral, i.e. with a flat side in profile, contents granular at maturity, hilar appendage inconspicuous, inamyloid; spore print white.
Solitary to scattered in duff of montane conifers; fruiting in the spring shortly after winter snows have melted; common.
Tricholoma vernaticum is recognized as much by a strong cucumber odor as its macroscopic features, i.e. a robust stature, greyish appressed-fibrillose cap, and stipe with an inconspicuous ring. Montane mushroom hunters often find this spring species while excavating duff mounds for King Boletes. Not the prettiest of mushrooms, the drab appearance of Tricholoma vernaticum is not helped by the dirt that frequently adheres to its surface. Tricholoma vernaticum is sometimes confused with Tricholoma saponaceum. The latter, however, has a glabrous, variably-colored cap, a mixture of greys, yellows, and olives, a soapy odor, and a pointed pinkish stipe base. Another spring Tricholoma, but not likely to be confused with Tricholoma vernaticum because of size, is Tricholoma moseri. A diminutive mushroom, it has a dark-grey, squamulose cap, greyish rather than cream-colored gills, and lacks a potato/cucumber odor and ring