Summary:
Features include 1) resupinate growth on decayed wood and bark, 2) a somewhat waxy fruitbody that is gray or bluish gray to light buff, under a lens appearing waxy-pruinose, 3) spores that are elliptic to suballantoid, smooth, weakly amyloid, and colorless, 4) basidia with the base often bifurcate, and 5) hyphae that are nodulose with clamp connections.

Microscopic:
SPORES 5-6.5 x 2-3.5 microns, elliptic and laterally depressed to suballantoid or allantoid, smooth, weakly amyloid, colorless; BASIDIA 4-spored, 7.5-16(24) x 4-5(6) microns, cylindric to subclavate, the base bifurcate, often obscure, sterigmata 4-7.5 microns long, subulate [awl-shaped], erect; SUBICULUM "either inconspicuous and giving rise to short, upright, nodulose hyphae, or rather thick and composed of hyphae parallel to the substratum, nodose-septate, 1-2.5 microns in diam, conglutinate or the walls becoming gelatinized", (Liberta), SPORES 5.5-6.5 x 2.5-3.5 microns, elliptic, "straight or more commonly depressed on one side, suballantoid, rounded above and below", smooth, weakly amyloid, thin-walled; BASIDIA 4-spored, 10-16 x 4-5 microns, clavate or subcylindric, "often bifurcate or inflated at one side", sterigmata 4-5.5 microns long, slender, erect; SUBHYMENIUM composed of hyphae 1.5-2.5 microns wide, intertwined, nodulose, thin-walled, with clamp connections; SUBICULUM "obscure below", (Jackson)

Notes:
Amyloxenasma rallum has been found in BC, OR, ON, IA, MA, NY, and RI, (Ginns).