Summary:
Features include 1) resupinate growth on wood, 2) fruitbodies that are thin and waxy, drying to ash-gray or ochraceous gray, the margin not well defined, 3) spores that are oblong to broadly ovate, and guttulate, and germinate by repetition, 4) basidia produced in clusters at the end of an ascending fertile hypha, leaving the previous basidia collapsed like an involucre lower on the fertile hypha, each new basidium splitting longitudinally into 2 to 4 cells, 5) dendrophyses or simple paraphysoids coming from clamp connections on the fertile hyphae, and 6) gloeocystidia that are cylindric or clavate-cylindric, with colorless then yellowish contents that become resinous. The neuter ending is correct for Greek nouns ending in -dendron (ICN Melbourne Code 62.2).

Microscopic:
SPORES (7)9-12(14) x 5-8(9) microns, oblong to broadly ovate, usually adaxially flattened, guttulate, germinating by repetition; PROBASIDIA 10-12-16.5 x 9-12-14 microns, obovate to ovate, granular-opaque, becoming 2-4-celled by longitudinal division, epibasidia 8-14-25 x 3 microns, subulate to subcylindric; hymenium consisting of erect fertile hyphae and gloeocystidia arising directly from substratum or subiculum, GLOEOCYSTIDIA 15-25-60 x 4-7(9) microns, "clavate to cylindric, often expanded at apex, flexuous, thin-walled, sometimes incrusted", colorless, then brownish, BASIDIA - fertile branches "erect, tortuous, 1-2 microns, the immature basidia clustered at the tips, borne terminally and on very short lateral proliferations from indistinct clamp-connections at the bases of older basidia, the clamps and proliferations and the collapsed walls of the older basidia forming a sheath about each fertile branch"; in section, 30-70(100) microns thick, the thicker parts with a granular subiculum of agglutinated hyphae, (Martin), SPORES 8-11(13) x 6-8 microns, "ovate to oblong, flattened on one side and slightly curved, guttulate, apiculate", "germinating by repetition or by germ-tube formation"; BASIDIA at the surface obovate, often elongating, becoming 2-celled to 4-celled by longitudinal septum, "with clamp connections at base and short lateral proliferations which grow out from indistinct clamps", sterigmata 8-15(25) x 2-3 microns, "cylindric with blunt apex, or subulate", probasidia 10.5-15 x 8-13 microns, pyriform to obovate; DENDROPHYSES or simple PARAPHYSOIDS present, 1-2 microns wide, "straight or tortuous, emanating from clamps on system of fertile hyphae, generally nonemergent"; GLOEOCYSTIDIA 16-35(60) x 4-7.5 microns, "flexuous, cylindric to clavate-cylindric, rarely incrusted", with colorless then yellowish contents that finally become resinous, fragmented, gloeocystidia "originating from a basal layer of indistinct hyphae or from clamps on fertile branches"; hyphae in a basal layer next to substrate composed of hyphae 1.5-2 microns wide that are indistinct, agglutinated, and horizontal, fertile branches ascending 1.5-2.5 microns wide, with "prominent nodes occurring along the sides of stalks subtending old and collapsed basidia forming an involucre and bearing at the apices, in clusters, younger basidia", (Luck-Allen)

Notes:
Basidiodendron cinereum has been found in BC, OR, ON, PQ, AZ, CA, IA, IN, LA, MI, NM, OH, and UT, (Ginns). It has also been found in Panama and Europe (Martin).

Synonyms and Alternate Names:
Bourdotia cinerea (Bres.) Bourdot & Galzin
Sebacina cinerea Bres.
Sebacina gloeocystidiata Kuehner
Sebacina murina Burt