Summary:
Inocybe assimilata is distinguished from similar species by an umber brown, distinctly cracked cap, a brown stem, and small, angular to obscurely nodulose spores, (Stuntz(1)). The description is derived from Stuntz(1) except where indicated.

Cap:
2.5-4cm across, bell-shaped, becoming expanded with low umbo; umber brown ("raw umber" to "mummy brown" at center, elsewhere "cinnamon brown" to "Prout's brown" or "Dresden brown"); lubricous when moist, drying silky-smooth, bald at center, elsewhere long-cracked

Flesh:
0.5cm at center, elsewhere thin; hygrophanous, pallid or ochraceous

Gills:
adnate, uncinate, emarginate, seceding at length, close, broad, 1.5cm x 0.5cm, ventricose, thin; "snuff brown", "Saccardo''s umber", "tawny olive", "Sudan brown", or "Brussels brown"; edges pallid-fimbriate [pallid-fringed], (Stuntz), creamy beige becoming grayish to reddish brown (Trudell)

Stem:
5-6cm x 0.4-0.5cm, equal or widening slightly downward, cylindric, solid or hollow; at first "Mikado brown" to "onion-skin pink" becoming "Verona brown" to "sayal brown", darker at base; satiny with a few superficial fibrils, white pruinose at top, white-mycelioid at base, (Stuntz), stem has rounded white bulb, (Moser), rounded bulb at base; reddish brown; "fibrillose over most of its length", "powdery at most at the apex", (Trudell)

Veil:
cap often bears faint grayish veil remnants (Trudell)

Odor:
none or faintly radish-like

Microscopic spores:
spores 6-8(9) x 4.5-6.5 microns, varying from angular to coarsely nodulose with 5-8 low obtuse nodules; pleurocystidia 36-50(60,75) x 10-17(21) microns, "fusiform-clavate to clavate above a slender pedicel, thick-walled apically", cheilocystidia "not very numerous, not projecting prominently, grouped in the clusters of sterile cells", sterile cells "numerous, cylindric to clavate or saccate, densely clustered, often mingled with basidia", gill trama "homogeneous, compact, the cells mostly rather short, inflated-cylindric or ventricose", "lactifers few, thread-like, small", (Stuntz), most septa with clamp connections, (Grund), spores 6.5-9.5 x 4.5-6.5 microns, weakly nodulose; pleurocystidia and cheilocystidia "slender to slightly ovate with thick walls, slightly narrowed necks, and crystals on the apices", (Trudell)

Spore deposit:
gray-brown (Buczacki)

Notes:
It has been found at least in WA, (Stuntz), and NS (Grund). Collections from BC are deposited at the University of British Columbia. The University of Washington has collections from WA, OR, and Denmark. It is widespread in North America, Europe, and temperate Asia, (Trudell(4)).

EDIBILITY

Synonyms and Alternate Names:
Inocybe umbrina Bres.