Summary:
Dendrocollybia racemosa is distinguished by its small size and the side branches on stem. The dry cap is grayish to brownish and typically small in relation to the length of the stem. The "branches" are actually the asexual state of the fungus that goes under the anamorph name Tilachlidiopsis racemosa. In 2006 it was shown that Russula crassotunicata is a host (Machnicki(1)).

Cap:
0.3-1cm across, obtusely conic, becoming flat or with slight obtuse umbo, margin usually curved in against gills at first; disc "fuscous", "drab" or paler toward margin; smooth, dry, opaque, innately silky, (Smith), 0.3-1cm across, bluntly conic to convex becoming umbonate to nearly flat; dark gray to gray or brownish gray, the margin often paler; smooth, not viscid, (Arora), 0.3-1cm across, convex and then flat with broad umbo, margin inrolled; medium brown, darkest at center; silky, (Kirkwood)

Flesh:
very thin, fragile; near drab; sclerotium "watery grayish and homogeneous in section, with a thin dull black outer coat", (Smith), thin, tough-pliant, (Kirkwood)

Gills:
sharply and narrowly adnexed, close, relatively broad; "wood brown" to "avellaneous"; edges even, (Smith), "typically adnexed, close"; gray or brownish gray, (Arora), somewhat paler than cap (Kirkwood)

Stem:
4-6cm long and 0.1cm wide, equal in upper part, tapering to a long root-like extension that ends in a dull black, more or less globular sclerotium 0.3-0.6cm in diameter, surface pruinose in upper part, "hair brown" to "fuscous", lower part of stem covered with irregularly arranged short branch-like protuberances 0.2-0.3cm long and 0.05cm wide, (Smith), 3-8cm x 0.05-0.3cm, "with numerous short lateral side-branches", especially over lower half or two thirds; gray to brownish gray, often entirely buried and sometimes originating from a small blackish bead-like sclerotium, (Arora), 3-5cm long, with projections 0.1-0.15cm in length coming out at right angles in lower half, stem arising from round, shiny, coal black sclerotium 0.2-0.7cm in diameter; stem colored as cap, may be buried entirely in substrate, (Kirkwood)

Veil:
[none]

Odor:
insignificant (Lincoff)

Taste:
not distinct (Castellano)

Microscopic spores:
spores 4-5 x 2 microns, narrowly elliptic; basidia 4-spored; pleurocystidia and cheilocystidia not differentiated, (Smith), spores 4-5.5 x 2-3 microns, oblong to elliptic, smooth, nonamyloid, asexual spores may be present on swollen tips of side branches, (Arora)

Spore deposit:
white (Arora)

Notes:
Dendrocollybia racemosa has been found at least in WA and ID, (Lennox), OR (Smith), and CA (Hughes). There are collections from BC at the University of British Columbia. It also occurs elsewhere including Belgium (Hughes).

EDIBILITY

unknown (Arora)

Synonyms and Alternate Names:
Collybia racemosa (Fr.) Quel.
Microcollybia racemosa (Pers.) Lennox