E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
{See also Dark Omphalinoid Arrhenia Table} Features include small size, a flat, hygrophanous, dark brown cap with a margin that is striate when moist and scalloped when old, gray-brown gills, an equal stem colored as the cap, and mild odor and taste. The description is derived from Bigelow(5).

Bigelow examined collections from BC, WA, ID, AK, MA, ME, and UT.

Cap:
0.5-1.6(3)cm across, convex with slightly depressed disc at first, margin appressed against stem then +/- incurved to decurved [downcurved], expanding to broadly convex or sometimes flat, "disc usually only narrowly and shallowly depressed"; hygrophanous, dark brown when moist ("bister", "mummy brown"), margin becoming somewhat paler when expanded, fading overall to brownish gray ("drab"); appearing bald or disc fibrillose, margin striate when moist, crenate [scalloped] when old

Flesh:
very thin, "soft and watery to pliant"; colored as cap surface

Gills:
broadly adnate then decurrent, distant, broad (about 0.3cm); grayish brown or brownish gray ("drab", "hair brown", "wood brown"); edges even, at times darker than faces

Stem:
1-2.5(3.5)cm x 0.05-0.1(0.2)cm, equal, "watery, fragile or pliant, stuffed"; colored as cap; unpolished, bald or sometimes pruinose to short pubescent [with short fine hairs]

Veil:
[presumably absent]

Odor:
not distinctive or rarely faintly fragrant

Taste:
not distinctive

Microscopic spores:
spores 7.5-10 x 5-6.5 microns, elliptic to broadly elliptic, smooth, inamyloid; basidia usually 4-spored but occasionally 2-spored, 18-28 x 5-6.5 microns; [pleurocystidia and cheilocystidia presumably absent]; clamp connections present