Cap 1.5-3.0 cm broad, obtuse-conic to convex, expanding to nearly plane, often with a low umbo; margin incurved when young, fringed with pale-lilac fibrils, eventually decurved to level; disc subglabrous, chestnut-brown to grey-brown, becoming fibrillose to squamulose and paler towards the margin, occasionally uniformly fibrillose and brown from disc to margin; context up to 4 mm thick at disc, tapering to 1 mm near margin, white, unchanging; odor not distinctive to faintly spermatic, or like Pelargonium, ie. geranium; taste mild.
Gills close, in youth ascending-adnexed, pale-lilac, becoming shallowly notched, then buff to dingy-light-brown, relatively broad, up 7 mm in width, conspicuously fringed, edges paler than the faces; lamellulae in three to four series.
Stipe 2.0-4.0 cm long, 4-7 mm thick, round, solid, brittle, straight to flexuous, equal to slightly enlarged at the apex and base; surface of apex pale-lilac, minutely hairy, the lower portion covered with lilac to pallid fibrils, over a light-brown to watery-brown, striate undersurface; context lilac-colored at the apex, buff-colored below; an evanescent fibrillose veil present between the immature cap and stipe.
Spores 8.0-10.5 x 4.5-6.0 µm, smooth, moderately thick-walled, almond-shaped in face-view, strongly inequilateral in profile, hilar appendage conspicuous; spores medium-brown in deposit; pleurocystidia and cheilocystidia common, lageniform to fusiform in shape, hyaline, thin to thick-walled, up to to 2 mm; thin-walled, club-shaped cells (paracystidia) abundant, interspersed with cheilocystidia; caulocystidia absent.
Scattered to gregarious under pines, especially Pinus radiata (Monterey pine) in the San Francisco Bay area; fruiting after fall rains; common. Associated with apsens in Montana and hardwoods in Europe. Also known from Michigan and Washington.
To be avoided; many Inocybe species contain the toxin muscarine.
A lilac-tinged cap margin and stipe are helpful though not definitive fieldmarks of Inocybe griseolilacina. To distinguish it from similar species requires a combination of characters and preferably young, fresh specimens. Inocybe griseolilacina is recognized by its appressed-fibrillose to slightly squamulose cap which is medium-brown at the disk, shading lighter brown and lilac-tinged towards the margin, the latter fringed in youth. Microscopic features include smooth spores, fusoid-ventricose to lageniform thick-walled, hyaline pleurocystidia and cheilocystidia, as well as the absence of caulocystidia. Of the lilac-colored Inocybes one is likely to encounter, Inocybe geophylla var. lilacina is easiest to recognize because of its silky-fibrillose cap which is entirely lilac when young except for a brownish disc. Inocybe pusio bears a strong resemblance to I. griseolilacina but its cap is uniformly brown and fibrillose with only the upper third of the stipe lilac. Another Inocybe with lilac to violaceous tones is Inocybe cincinnata (=I. phaeocomis). The two varieties of this species have scaly brown caps, also with only the upper portion of the stipe typically lilac. Microscopically they differ in possessing thick, yellow-walled pleurocystidia and cheilocystidia as well as brown, incrusted paracystidia interspersed among the cheilocystidia; additionally, caulocystidia are present only at the extreme apex of the stipe.