Plants whitish green to yellowish green. Stems 1--5 (--10) cm. Leaves erect-spreading to falcate-secund, 2--8 ? 0.5--1 mm, entire or with a few serrulations near apex; costa covering ca. 9/10 or more of leaf base, smooth on abaxial surface, in cross section with a row of adaxial hyalocysts, a row of median chlorocysts and a row of abaxial hyalocysts. Seta 10--20 mm. Capsule 2--3 mm; operculum 1--1.5 mm. Spores 15--20 µm.

Capsules mature summer. Usually on soil or soil over boulders, noncalcareous outcrops and cliffs, sometimes in bogs and fens, rarely on stream banks; 150--4300 m; Greenland; Alta., B.C., N.W.T., Yukon; Alaska, Ariz., Colo., Mont., N. Mex., Utah, Wyo.; Mexico; Europe; Asia.

This species is best distinguished from P. longifolium by its whitish green to yellowish green color, nearly smooth leaf margins that occasionally have a few teeth near the apex, and smooth costa. Sporophytes are more rarely produced than is the case with P. longifolium.