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

Summary:
Features include 1) a convex to vase-shaped cap that is blackish brown, usually streaked with lighter brown and paler on the disc, 2) decurrent, distant, white to gray gills, 3) a brownish stem that has dark scales at top and becomes paler with age, 4) mild odor and taste, 5) growth on humus or rotting hardwood, 6) white spore deposit, and 7) round to elliptic amyloid spores. The molecular study of Antonin(2) showed an affinity with Gerronema rather than Clitocybula sensu stricto.

Collections of Gerronema atrialba were examined from WA, OR, CA, (Bigelow(3)). It has been found in BC (Bandoni, Lowe).

Gills:
decurrent, ends even and forming a collar on stem top, distant, narrow or broad, occasionally forked when old; grayish ("tilleul buff", "smoke gray"); intervenose, faces venose, (Bigelow), decurrent, distant, moderately broad, sometimes forked; mentioned as ''whitish'' and as ''grayish''; veined, (Lincoff), well-spaced; white to grayish, (Arora)

Stem:
6-10.5(12)cm x 0.4-1.2cm, base somewhat enlarged; brown ("buffy brown", "olive brown"), paler when old; diffracted scaly to furfuraceous at top, fibrillose-streaked downward, top with ridges as continuation from gills, base often with rhizomorphs, (Bigelow), 5-12.5cm x 0.3-1.5cm, enlarged at base; brownish; scaly and fibrous streaked, (Lincoff), clothed with dark scurfy scales (Arora)

Odor:
not distinctive (Bigelow)

Taste:
not distinctive (Bigelow)

Microscopic spores:
spores (6)7.5-9 x 7-8 microns, from 4-spored basidia, round or nearly round, (up to 13 x 9 microns, from 1- and 2-spored basidia, then broadly elliptic to subovate), smooth, amyloid; basidia (30)36-50(56) x 6.5-9.5 microns, often 2-spored, occasionally 4-spored and 1-spored; pleurocystidia none, cheilocystidia none; clamp connections present, (Bigelow), spores 6-11 x 6-10 microns, more specifically 9-11 x 7-9 microns and elliptic or 6-10 microns and round; smooth, amyloid, (Lincoff)

Spore deposit:
white (Bigelow, Lincoff)