Summary:
Features include 1) resupinate growth on very rotten wood, 2) fruitbodies that are thin, waxy, and whitish to pale gray, 3) spores that are nearly round with a prominent apiculus, inamyloid, and smooth to finely punctate, germinating by repetition or by germ tubes produced at the non-apiculate end, 4) basidia longitudinally septate and borne in clusters of 2-3 at the ends of fertile hyphae that are sheathed on the sides by collapsed basidia, each new basidium splitting longitudinally into 2 to 4 cells, and 5) ascus-shaped gloeocystidia that sometimes have brown content and may have capitate ends. The neuter ending is correct for Greek nouns ending in -dendron (ICN Melbourne Code 62.2).

Microscopic:
SPORES 8 x (5)6-7.5 microns, nearly round, inamyloid, smooth to very finely punctate, colorless, with drops, with distinct apiculus; HYPOBASIDIA 10-15 x 7-9(10) microns, oval, longitudinally septate, with 2-4 epibasidia; GLOEOCYSTIDIA 30-50 x 6-9 microns, ascus-shaped, sinuous, sometimes with brown contents; hyphae 1-3 microns wide, gelatinized, "with gnarled branches, indistinctly visible", no septa observed, (Breitenbach), SPORES 5-7.5 in diameter, round, "with peglike apiculi 1-2 microns long"; fertile hyphae "erect, tortuous, subdistinct", 1-1.5 microns wide, "each bearing 2-3 basidia at the apex and a sheath of collapsed basidial walls down the sides", probasidia "at first obovate, finally ovate", colorless, 10-13.5 x 7.5-8.5 microns, "becoming tardily and indistinctly two to four-celled by longitudinal division", epibasidia 5-8 microns long including sterigmata, 3 microns thick at base; GLOEOCYSTIDIA 25-40(60) x 4-8(15) microns, "cylindric-clavate, sinuous, often expanding apically into globose heads up to 15 microns in diameter", with contents at first colorless, soon brownish, (McGuire), SPORES 5-9 microns in diameter, round, "very minutely roughened, at times roughening indistinct", "prominent apiculus measuring up to 2 microns, germinating by repetition or by germ tubes produced at the non-apiculate end"; BASIDIA at first 2-celled, "eventually 4-celled with septum at times indistinct", 11-17(19) x 8-10, urniform, elongate, "produced in groups of 2-3(4) terminally on fertile axis", sterigmata 5-12 microns long, "subulate, divergent, or incurved", PROBASIDIA 9-13 x 5-8 microns, obovate, with clamp connections at bases; GLOEOCYSTIDIA 15-50 x (3)4.5-8(18) microns, "cylindric, sometimes tapering toward the apex, cylindric-clavulate or irregular with contents hyaline, then yellowish, finally resinous, fragmented, infrequently septate, flexible, non-projecting"; hyphae in a thin horizontal layer, at times agglutinated, running parallel with substrate and connecting up with erect, ascending, fertile and sterile hyphae, fertile hyphae 2-3(4.5) microns wide and up to 45 microns long, "nodulose, tortuous, ascending", "with a sheath of collapsed basidia extending down the sides of the fertile columns almost to the base", (Luck-Allen)

Notes:
Basidiodendron caesiocinereum has been found in BC, OR, ON, PQ, AZ, FL, IA, MA, ME, MO, NM, NY, and RI, (Ginns), North America, Europe including Switzerland, Asia, and Africa, (Breitenbach), and Hawaii and Austria, (Martin).

Synonyms and Alternate Names:
Bourdotia caesiocinerea (Hoehn. & Litsch.) Bourdot & Galzin
Corticium caesiocinereum Hoehn. & Litsch.
Corticium echinosporum Ellis
Sebacina caesiocineria Hoehn. & Litsch.) D.P. Rogers
Sebacina cinerella (Bourdot & Galzin) Killerm.
Tomentella echinospora (Ellis) Bourdot & Galzin