Plants soft, in small, loose tufts, light to very dark green. Stems 1-2.5 cm. Branch leaves strongly crisped and curled when dry, ovate-lanceolate, abruptly subulate, entire or sometimes serrated above, 3-6 mm, subtubulose above, strongly sheathing at base, margins plane; costa mostly percurrent; laminal cells mostly 1-stratose, 2-stratose only at margins; distal laminal quadrate to short-rectangular, incrassate; basal laminal cells elongate, rectangular, incrassate, alar cells not differentiated. Seta (8-)10-15(-21) mm. Capsule pale yellow-brown, furrowed when dry, 0.8-2 mm, peristome bright red. Spores 14-20(-30) µm.
Capsules mature late spring-early summer. Rotten logs along streams or in flooded areas, less commonly on soil, humus, rock or bark at the base of coniferous trees (e.g., Thuja); Greenland; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia.
A common epixylic species, Oncophorus wahlenbergii may be confused with the more saxicolous O. virens, which has keeled, revolute, non-sheathing leaves that gradually narrow to the subula. A compact, densely tufted arctic-alpine form has been treated as var. compactus and is often found on dry soil.