Summary:
Clitocybe nebularis is distinguished by its large size, grayish brown cap that often has a hoary bloom or watery spots, and rancid disagreeable odor.

Cap:
6-25cm across or more, convex becoming flat or depressed, margin incurved at first, often wavy or lobed when old; gray to grayish brown to buff, often darker at center; "sometimes with watery spots or appearing streaked"; "dry, finely fibrillose or often with a hoary bloom", (Arora), (4.5)9-15(25)cm across, convex with incurved margin, becoming flat but margin often remaining downcurved, disc shallowly depressed or somewhat umbonate; non-hygrophanous, grayish or light brownish gray; moist, subviscid in wet weather, radiate-fibrillose or sometimes canescent [hoary] in places, margin occasionally sulcate-striate or incised, (Bigelow)

Flesh:
thick; white, (Arora), "thick on disc, tough but pliant"; white, (Bigelow)

Gills:
"adnate to decurrent, close"; "whitish becoming dingy yellowish or buff", (Arora), adnate at first, soon becoming short decurrent, finally moderately decurrent, close, broad in middle, up to 1cm, but narrowed at stem and cap margin, forked, not interveined; white or faintly cream-colored, ("cartridge buff", "cream"), edges even but brittle and becoming eroded and incised with age, (Bigelow)

Stem:
6-15cm x 1.5-4cm, base often widened, firm but easily broken; whitish or with dingy brownish fibrils; base often covered with white down, (Arora), (5)7-10(15)cm x (1.5)2.5-4cm, off-center at times, often curved, compressed (flattened) at times, solid, base enlarged or bulbous; light gray-brown fibrils over a whitish ground color, more or less dingy over all when bruised; base usually with copious white tomentum, (Bigelow)

Odor:
rancid and disagreeable, likened to rancid flour, rotting cucumbers, skunk cabbage, mice cages, beer barf, (Arora), usually disagreeable, sometimes sour or slightly farinaceous, rarely mild, at times recalling skunk, (Bigelow)

Taste:
usually disagreeable, sometimes sour or slightly farinaceous, rarely mild, (Bigelow)

Microscopic spores:
spores 5.5-8.5 x 3.5-4.5 microns, elliptic, smooth, (Arora), spores 5.5-8.5 x (3)3.5-4.5 microns, elliptic, smooth, inamyloid, wall cyanophilic; basidia usually 4-spored, rarely 1-spored or 2-spored, 20-33 x 3.5-7 microns, [presumably no pleurocystidia or cheilocystidia]; clamp connections present, (Bigelow)

Spore deposit:
pale buff to yellowish, (Arora), pale yellow (Bigelow)

Notes:
Collections were examined from BC, WA, OR, ID, AK, CA, MI, Denmark, Norway, and Sweden (Bigelow). It is illustrated for Switzerland (Breitenbach). It has been reported from Mexico (Bigelow).

EDIBILITY

yes if thoroughly cooked, flavor poor, (Arora), may cause allergic upset, (Lincoff(1)), take care to distinguish from Entoloma species

Synonyms and Alternate Names:
Clitocybe avellanea (Murrill) Singer
Clitocybe oreades Murrill
Lepista nebularis (Fr.) Harmaja
Melanoleuca avellanea Murrill
Tricholoma avellaneum Murrill