Inocybe geophylla
lilacina
Les Hyménomycètes: 520. 1876.
Common Name: none
Synonym: Inocybe lilacina (Peck) Kauffman
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.
Toxic.
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.
Kobayashi, Takahito (2002). The taxonomic studies of the genus Inocybe. Nova Hedwigia Beiheft 124. J. Cramer: Berlin. 246 p.
Kuyper, Thomas W. (1986). A Revision of the Genus Inocybe in Europe. I. Subgenus Insperma and the Smooth-Spored Species of Subgenus Inocybe. Rijksherbarium: Leiden, Netherlands. 247 p.
Smith, A.H. (1949). Mushrooms in their Natural Habitats. Sawyer's Inc: Portland, OR. 626 p.