Plants in dense tufts, light green, glossy. Stems 4.5--10 cm, tomentose throughout with brown to red rhizoids. Leaves erect-spreading, erect-appressed when dry, smooth, (2.5--)3--4(--6.5) ´ 0.3--0.5 mm, from an ovate-lanceolate base to a tubulose subula, narrowly obtuse at apex, rarely acute, sometimes apical leaves of stems julaceous; margins entire; laminae 1-stratose, occasional 2-stratose regions near costa in proximal part of leaf; costa subpercurrent to percurrent, 1/10--1/6 the width of the leaves at base, smooth, abaxial ridges lacking, with a row of guide cells, two well-developed and thick stereid bands (5--6 cells thick), adaxial epidermal layer of cells not differentiated, the abaxial layer usually with a few cells enlarged; cell walls between lamina cells slightly bulging; leaf cells smooth; alar cells 1- or 2-stratose, well-differentiated, not extending to costa; proximal laminal cells elongate-sinuose, strongly pitted, (36--)54--65(--98) ´ (2--)5--6(--9) µm; distal laminal cells (11--)17--26(--42) ´ (2--)5--6(--12) µm. Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing. Seta 1.5--2 cm, solitary, yellow to reddish yellow. Capsule 1.5--2 mm, nearly straight and erect to slightly arcuate, ± striate when dry, yellowish brown; operculum 1--1.7 mm. Spores 14--19 µm.

Capsules mature in summer. Arctic or alpine tundra, soil, humus or rocks, sometimes in bogs and fens; 10--3800 m; Greenland; Alta., B.C., Man. Nfld., N.W.T., Nun., Ont., Que., Yukon; Alaska, Colo., n N.Y.; Europe; Asia.

This Arctic-alpine species is sometimes not a very distinct species, often being difficult to separate from its nearest relative, D. elongatum. For distinctions see the discussion under that species.