Plants 0.5--2 mm. Leaves lingulate to suborbicular, 0.5--1.5 mm, margins entire, undulate-denticulate distally, differentiated at base, apex cucullate to nearly open; costa subpercurrent, filaments 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, 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; 100--1500 m; Greenland; Alta., B.C., Man., Nun., N.W.T., 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.