Summary:
Features include 1) resupinate growth on wood, 2) a cottony, separable, continuous fruitbody that is dull ferruginous, the surface smooth to granulose or toothed, the margin paler and fringed to fibrillose, the subiculum thin and dark ferruginous brown, and cordons usually visible under 10x lens, 3) spores that are round to nearly round, verrucose to aculeolate, and brown, and 4) subicular hyphae of three types.

Microscopic:
SPORES (4)5-6 microns diameter, or 5-6 x 4.5 microns, round to nearly round, verrucose to aculeolate, "pale brown to umbrinous"; BASIDIA 4-spored, 30-40 x 6-7(8) microns, clavate, often with a median constriction, with a clamp connection at the base, rarely with transverse septa, sterigmata up to 6 microns long; SUBHYMENIAL HYPHAE 2-3.5 microns wide, pale yellow, thin-walled, with clamp connections; TRAMAL HYPHAE of 2 types: 1) some generative, 2-4.5 microns wide, "forming a distinct central core and projecting somewhat at the sterile apices", yellowish brown, wall thickening apparent, with clamp connections, "often with an ochre or brown agglutinating material which dissolves, resulting in a similarly colored diffusate", 2) some skeletal, 1-2 microns wide, yellow, thick-walled, aseptate; SUBICULAR HYPHAE of 3 types: 1) some generative, 2-3(4) microns wide, yellowish brown, wall thickening apparent, normally septate, with frequent clamp connections, "often encrusted with granular material which sometimes gives the hyphae a spinulose appearance", 2) some generative, 3-5 microns wide, "thin-walled, often collapsed, rarely branched", usually septate, with infrequent clamp connections, "often aseptate for relatively long distances", 3) some skeletal, 1-2 microns wide, bright yellow to citrine, thick-walled, usually aseptate, rarely with septate; CORDONS up to 40 microns wide, yellowish brown, individual hyphae "mostly thin-walled, 2-3.5 microns diam, clamped", (Larsen)

Notes:
Tomentella calcicola has been found in BC, WA, ID, AB, CO, IA, MT, and NY, (Ginns), as well as Belgium, France, and Russia, (Larsen).

Synonyms and Alternate Names:
Phacidium medicaginis Lib.