Summary:
Features include 1) a brownish, moist to slightly viscid, fibrillose cap with a prominent black nipple, 2) close, broad whitish gills that become gray-brown, 3) a whitish stem sheathed below the ring zone with dark brown to olive brown fibrils and pruinose at the top, 4) spermatic odor, and 5) smooth spores, Lincoff(2) says, "This is one of the few easily recognized inocybes among the more than 500 species in North America."

Cap:
1-2.5cm across, conic becoming bell-shaped to broadly convex and finally flat with a prominent umbo when old; umbo dark brown, cap "covered with dark brown to dull brown, radially flattened fibrils over a pale buff to whitish ground color"; smooth and subviscid over disc, otherwise moist to dry, (Bessette), 1-2.5cm across, conic to bell-shaped, becoming nearly flat with prominent nipple; brownish with blackish nipple; moist, smooth to minutely fibrous, (Lincoff), in wet weather, surface feels lubricous to viscid, despite the lack of a gelatinous cap cuticle, (Grund)

Flesh:
whitish to pale buff (Bessette)

Gills:
"attached, close, broad"; "cream at first, becoming pale brown to gray-brown at maturity", (Bessette), "attached, close, broad"; "whitish, becoming grayish brown", (Lincoff)

Stem:
4-7.5cm x 0.15-0.3cm, equal, somewhat bulbous at base; sheathed from base to ring zone with dark brown to olive-brown fibrils over a whitish ground color; pruinose at top, ring zone evanescent [fleeting], (Bessette), 5-7.5cm x 0.15-0.3cm, off-white to gray, with minute fibers, tip minutely hairy, (Lincoff)

Veil:
no ring (Bessette)

Odor:
unpleasant, spermatic, (Bessette), spermatic (Lincoff)

Taste:
not distinctive (Bessette)

Microscopic spores:
spores 7-10 x 4.5-6 microns, elliptic, smooth, pale brown, (Bessette), spores 7-10 x 4.5-6 microns, elliptic, smooth, brownish, (Lincoff), spores 8-10 x 4.5-5.5 microns, mostly 9 x 5 microns, occasional ones up to 12-13 microns long from 2-spored basidia, inequilaterally almond-shaped, usually with bluntly rounded apex; basidia mostly 4-spored, occasionally with 2 spores, 21-24 x 6.5-8 microns, clavate; pleurocystidia 45-65(77) x (12)14-22(30) microns, mostly 50-55 x 16-20 microns, "ventricose above a slender pedicel, with cylindric or slightly tapering neck", moderately thick-walled (1-2 microns), colorless in 3% KOH, cheilocystidia of 2 kinds, some resembling pleurocystidia, others 18-33 x 10-13 microns, thin-walled, clavate; gill trama parallel, of compactly arranged hyphae with cells 10-30 microns wide, varying from cylindric to broadly fusiform; cap surface at the center a layer about 300 microns deep of intricately woven hyphae 5-8 microns wide, with smooth, colorless to slightly colored walls and gray-brown vacuolar pigment, toward the margin this cuticular layer becoming thinner (100-180 microns deep), and the surface hyphae tending to be parallel to the surface, those below remaining loosely interwoven; apex of stem with abundant, dense clusters of dermatocaulocystidia, some like the pleurocystidia in wall thickness, but clavate to fusoid, and up to 85 microns long, "others thin-walled, varying greatly in size and shape, mostly clavate", about 20-50 x 14-20 microns, "base with abundant tangled superficial hyphae bearing numerous cylindric or clavate terminal cells, no dermatocaulocystidia"; laticiferous hyphae not seen; clamp connections present on almost all septa, (Grund)

Spore deposit:
brown (Bessette, Lincoff)

Notes:
There are collections for BC at the University of British Columbia and collections for WA and VT at the University of Washington. It was noted for CA by Nishida. Grund gives the distribution in North America as WA, CA, MI, NY, and TN.

EDIBILITY

poisonous (Lincoff)