Bot. Not. 1868: 72. 1868.
Plants 3–8(–12) cm. Stems dark reddish brown. Leaves green, reddish brown, or black when old, erect-spreading, ± flat, not strongly reflexed when moist, broadly elliptic, ± orbicular, spatulate, occasionally ovate or obovate, 3.5–6 mm; base short-decurrent; margins plane or weakly recurved, 2- or 3-stratose; apex rounded, obtuse, or rarely retuse, apiculate or sometimes not, apiculus blunt; costa percurrent, excurrent, or rarely subpercurrent; medial laminal cells elongate, (40–)70–110 µm, in diagonal rows, weakly collenchymatous; marginal cells short-linear or linear, in 3 or 4 rows. Sexual condition synoicous. Seta yellowish, 4–6 cm. Capsule yellowish, subglobose, 1.5–2.5 mm. Spores 25–70 µm.
Phenology: Spores 25-70 µm, mature summer.
Habitat: Peat and deep organic soil to shallow wet mineral soil on rock in fens, along river banks
Elevation: low to moderate elevations
Greenland, Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Que., Yukon, Alaska, Mich., Europe.
Cinclidium subrotundum is distinguished by its broadly elliptic, nearly orbicular or spatulate leaves usually ending in a small, blunt apiculus. When present, the subglobose capsules are also diagnostic.