Summary:
Features include 1) a fragile brown cap with an overlying whitish to grayish fibrillose layer, 2) an eccentric to lateral stem if present, 3) farinaceous odor and taste, 4) growth on wood or on the ground in protected humid situations, 5) a pinkish spore deposit, and 6) angular spores. It is common in the western United States (Largent(1)), and the commonest Claudopus in the Pacific Northwest. Claudopus avellaneus Murrill from Oregon could be a more appropriate name for this species in western North America (Siegel(2) discussing California).

Cap:
0.5-7.5cm broad and 0.5-4.5cm long, orbicular, becoming petaloid [petal-shaped] or fan-shaped, or even dimidiate, margin even when young, undulate [wavy] and uplifted to upturned with age, incurved at all times; not hygrophanous, dark brown then brownish orange to light brown, at first covered by a whitish to grayish white canescent-like [hoary] to appressed-fibrillose mycelial layer that is quite dense toward base, minutely pubescent at times, opaque at first but becoming translucent-striate, (Largent)

Flesh:
thin, up to 0.05cm, fragile; tan, (Largent)

Gills:
"adnexed, close to subdistant, moderately broad to broad", 0.2-0.6cm broad; grayish to grayish brown, [presumably becoming pinkish brown], edge colored as face; edge smooth, (Largent)

Stem:
0.3-0.8cm long, 0.15-0.4cm wide at top, 0.05-0.2cm broad at base, (when present, but fruitbody can also be resupinate to effuso-reflexed), narrowing downward, centrally attached in button stage, quickly becoming laterally to eccentrically attached, stuffed then hollow; pale tan; densely appressed-fibrillose, "on drying becoming minutely pubescent", white rhizomorphs arising from tuft of mycelium at base of stem, with same rhizomorphs attached to several fruiting bodies at a time, (Largent)

Odor:
farinaceous (Largent)

Taste:
farinaceous (Largent)

Microscopic spores:
spores 7.4-11.5 x 5.3-8.2 microns, angular, heterodiametric; basidia clustered into dense clumps when squashed, 32.7-48.6 x 7.4-14.7 microns; pleurocystidia absent, cheilocystidia most typically absent, at times and only on a few gill edges rare to scattered, 36.9-55.8 x 4.8-5.8 microns, cylindric to cylindroclavate, irregular in outline; clamps abundant at base of basidia, rare on loose hyphae that cover pileipellis, rare in pileipellis; pigmentation "intracellular and very pale in loose hyphae and in hyphae of pileipellis", "minutely incrusted on thin hyphae in trama and sometimes on hyphae of pileipellis, incrustations difficult to see", (Largent), spores 8-12 x 5.5-7 microns, elongate elliptic, nodulose angular, inamyloid, "pale pinkish honey in alkali and water"; basidia 4-spored with basal clamp connection; pleurocystidia absent, cheilocystidia absent or undifferentiated clavate cells, cap cuticle a cutis of radially arranged hyphae 4-10 microns wide with brownish gray membranal pigmentation, (Watling)

Spore deposit:
clay pink (Watling), pinkish brown (Miller)

Notes:
Collections were examined from WA, OR, ID, CA, and WY, (Largent). It was reported from BC by Oluna Ceska (pers. comm.). Breitenbach(4) give the distribution as North America, Europe, and North Africa. Watling(2) lists it for United Kingdom.

EDIBILITY

Synonyms and Alternate Names:
Entoloma byssisedum (Pers.: Fr.) Donk