Plants 0.5-2 mm. Leaves lingulate to suborbicular, 0.5-1.5 mm, margins entire, undulate-dentic-ulate distally, differentiated at base, apex cucullate to nearly open; costa subpercurrent, fila-ments of 2-5 cells, cells subspheric to cylindric; cells of leaf base 13-66 µm, medial and distal cells 13-40 µm, papillae none. Sexual condition synoicous or dioicous. Seta 6-17 mm. Capsule urn cylindric, 1-2 mm; operculum conic, short-rostrate, erect or inclined, 0.5-1 mm; peristome 250-900 µm, twisted. Spores 15-25 µm.
Capsules mature (Mar-)May-Aug. Bare or disturbed soil or silt, roadside banks, calcareous boulders or gravel; low to moderate elevations (100-1500 m); Greenland; Alta., B.C., Man., N.W.T., Nunavut, Ont., Yukon; Alaska, Mont.; Europe; Asia (Siberia).
The leaves of Aloina brevirostris are usually short, and cucullate with a reduced lamina; forms with larger laminae may be confused with A. rigida, but the synoicous condition and the cylindric capsules with a conical operculum are diagnostic. The latter species is dioicous, and has ovoid-cylindrical capsules with a long-rostrate operculum.