Summary:
Features include 1) membranous-tomentose, mould-like, continuous growth on wood, 2) a ferruginous brown fruitbody (gray to somewhat violet when young) that is smooth, mealy, and faintly reticulate, the subiculum and margin darker, 3) round to nearly round, yellow spores with spines up to 3 microns long, and 4) basidia with transverse septa, and pale yellow encrusting material often on walls, 5) a monomitic hyphal system, the hyphae with clamp connections, and 6) subicular hyphae of 2 types. Tomentella bryophila is "for the most part, readily diagnosed by its bright ferruginous fertile areas and large, normally globose, aculeate, yellow basidiospores. However, it grades morphologically into T. fuscoferruginosa, which has irregular spores and apparently only one kind of subicular hyphae. The distinction between the two is by no means clear." (Larsen, Latin name in italics).

Microscopic:
SPORES 7-11(12) microns in diameter, round to nearly round, sometimes irregularly round, normally aculeate, sometimes echinulate, pale to bright yellow; BASIDIA 4-spored, 50-60 x 7-9(11) microns, clavate, with clamp connection at base, transverse septa present, "pale yellow encrusting material frequently present on basidial walls", sterigmata up to 6 microns long; SUBHYMENIAL HYPHAE 4-6 microns wide, "thin-walled, sometimes with local thickenings", with clamp connections, pale olivaceous brown to colorless, or becoming bright yellow due to yellow encrusting material; SUBICULAR HYPHAE of 2 types: 1) some 4.5-6(7) microns wide, closely spaced, dull olive brown, "thick-walled and often with localized thickening", with clamp connections frequent, 2) some 4-6 microns wide, violaceous brown, thin-walled to thick-walled, often with localized thickenings, "clamped, septa without clamps infrequent", (Larsen), SPORES (7)8-10 microns in diameter, excluding spines, nearly round, with pointed spines up to 3 microns long, spore brown; BASIDIA 4-spored, 50-60 x 8-11 microns, cylindric-clavate, with basal clamp connection; CYSTIDIA not seen; HYPHAE monomitic brown, thin-walled to thick-walled, hyphae of subhymenium 4-6 microns wide, of subiculum 4-8 microns wide, septa with clamp connections; hyphal strands absent, (Breitenbach)

Notes:
Tomentella bryophila has been found in BC, ID, MB, ON, AZ, CO, DC, FL, GA, IL, IN, LA, MA, MD, MI, MN, MT, NC, NM, NY, OH, PA, TN, and VT, (Ginns), as well as Austria, Czechoslovakia, Denmark, Finland, France, Germany, Hungary, Italy, Netherlands, Norway, Poland, Sweden, United Kingdom, Tunisia, and Pakistan, (Larsen).

Synonyms and Alternate Names:
Cordyceps ravenelii Berk. & M.A. Curtis