Summary:
Features include 1) tiny fruitbodies growing on roots of commercial grapes, the fruitbodies consisting of a spherical, light gray, powdery spore mass and a slender, light yellow, smooth stem, and 2) microscopic characters. The description here is derived from that of Dennis(1) for Roesleria pallida, this description being one specified by Redhead(65) for Roesleria subterranea in making the new combination.

Microscopic:
spores 5-6 x 4-5 microns, broadly elliptic, smooth, colorless to light greenish gray, uniseriate in the ascus; asci 8-spored, up to 55 x 10 microns, cylindric, soon vanishing; slender hyphae among the asci "have been called paraphyses but there is no compact hymenium"; stem consisting of hyphae about 3-4 microns wide, compact, parallel, thin-walled, the hyphae becoming loose and radiating in the head, (Dennis), spores have pale isabelline wall pigmentation; a septum divides the spores across their broadest plane but is only visible in lateral views (liquid mounts most often show the polar view because of the orientation of the slightly compressed sides against the slide surface); spores of Roesleria are described as roughened (at least under scanning electron microscope), (Redhead)

Notes:
Collections of Roesleria subterranea were examined from BC, France (slide only), and Germany, (Redhead).

Synonyms and Alternate Names:
Thelephora salicina Fr.