A smut fungus on ovaries of Carex pulicaris, visible as black masses (hard or powdery) in often-stunted inflorescences. Probably more easily seen in older inflorescences.
Sori in ovaries, scattered in infloresences, forming ovid to ellipsoidal, black, hard bodies, 2-2.5 mm long, powdery on the surface, partly enclosed by the longitudinally splitting utricles. Spores medium-sized, occasionally subglobose to ellipsoidal, usually irregular, subangular and flattened, 12-21 x 17-24(-26) µm, dark reddish brown; wall 1-3.5 µm thick, thickest at the angles, often with light-refractive areas, internal swellings small, 1-3 or absent, surface densely and conspicuously verrucose, warts forming groups or rows, sometimes fusing, spore profile smooth, undulate or finely serrulate.
On Carex pulicaris in North and Central Europe.
Description adapted from Vánky, K. (2012). Smut fungi of the world. St. Paul, Minnesota: APS press.