Cap 1.0-2.5 cm broad, convex, expanding to nearly plane, the disc occasionally slightly raised; margin at first decurved, then plane, not striate, or if so, obscurely; surface dry, glabrous at the disc, sometimes becoming fibrillose toward the margin; color: tan-brown at the disc, shading to buff-brown at the margin; context thin, less than 1 mm thick, colored like the cap; odor and taste mild.
Gills adnexed, sometimes appearing free, crowded, narrow, pallid, becoming pale-buff in age; lamellulae up to 4-seried.
Stipe up to 5.0 cm long, 0.5-1.5 mm thick, round, equal, pliant; surface pruinose, pallid to buff at the apex, becoming dull vinaceous-buff below, the base hairy, non-instititious; partial veil absent.
Spores 3.0-4.0 x 2.0-2.5 µm, ellipsoid, smooth, amyloid; spore print white.
Solitary to clustered on cones of Douglas fir (Pseudotsuga menziesii), and Sitka spruce (Picea sitchensis); fruiting from late fall to mid-winter.
Baeospora myosura is one of a relatively small number of mushrooms that fruit primarily on conifer cones. It is recognized by a tan, glabrous to appressed-fibrillose cap, crowded gills, and a stipe that is pallid at the apex and brown to pale vinaceous-brown at the base. It is often confused with Strobilurus trullisatus, also common on Douglas fir and Sitka spruce cones, but the latter has a whitish, striate cap, close, not crowded gills, and a stipe that is pallid at the apex, shading to a yellowish to tawny-brown base. The two species are also distinct microscopically, Baeospora myosura having a cuticle of repent hyphae and small, amyloid spores while Strobilurus truillisatus has a cellular type cuticle and somewhat larger, inamyloid spores.