Inocybe geophylla var. lilacina
Cap 1.5-2.5 (3.0) cm broad at maturity, ovoid in button-stage, becoming obtuse-conic to campanulate, plane to plano-depressed in age, typically with a low umbo; immature margin adherent to stipe, fibrillose, incurved, then decurved, eventually plane to slightly raised; surface at first pale-lavender, glabrous to innately streaked, disc tan-brown; mature caps appressed-fibrillose, straw-brown to dull-tan; context thin, 2-3 mm thick at the disc, elsewhere <1 mm, pallid to pale-tan, unchanging; odor indistinct; taste mild, sometimes with a faintly bitter aftertaste.
Gills adnexed to inconspicuously notched with a descending tooth, close, pale-lavender when young, fading to whitish, in age buff-brown to pale-grey; gill edges fringed (use hand-lens); lamellulae up to four-seried.
Stipe 2.0-5.0 cm long, 2.0-4.0 mm thick, equal to slightly enlarged at the base, round, stuffed to hollow at maturity; surface in youth, pale lavender, pruinose to minutely hairy, in age nearly glabrous or with scattered appressed hairs, fading like the cap to pale-tan; partial veil evanescent, fibrillose, lavender-colored (best seen in young material), leaving sparse fibrils in an annular zone high on the stipe.
Spores 9.0-11.0 x 4.5-6.0 µm, elliptical, smooth, thin-walled, hilar appendage evident; spore print dull brown.
Scattered to gregarious under hardwoods and conifers; fruiting after the fall rains to mid-winter; occasional.
This lilac-colored form of Inocybe geophylla resembles a number of small Inocybes with lavender hues in their stipe, gills, or cap. None of these, however, have a glabrous cap when young. Also similar is Mycena pura, a species that is distinguished by a striate cap margin, radish odor, and white, not brown spores. Clitocybe nuda and several Cortinarius species, while possessing lilac-colored caps, are unlikely to be confused due to their much larger size. Inocybe geophylla var. geophylla, the white form of the species, is typically more common in California.