A smut fungus on the ovaries of Carex limosa, visible as black masses in often-stunted inflorescences. Possibly more visible in older inflorescences.
Sori in ovaries, scattered in inforescences, forming subglobose, black hard bodies, 2-3 mm in diam., powdery on the surface. Spores large, flattened, in side view 13-17 µm wide, in plane view subcircular, broadly elliptic or subangular, 15-30 x (19-)20-33(-35) µm, dark reddish brown; walls even, 1-2.5 µm thick, no internal swellings, no light-refractive spots, surface verrucose, warts 0.1-0.6 µm high forming short rows or small groups, in SEM with moderately dense, fine to coarse, rounded, sometimes confluent warts, the surface between them finely, densely verruculose, appearing rough. Rather variable in spore size and ornamentation.
Description adapted from Vánky, K. (2012). Smut fungi of the world. St. Paul, Minnesota: APS press.