Plants in dense tufts or mats, green to dark green to brownish-green. Stems 0.3--1 cm. Leaves loosely imbricate, somewhat contorted when dry, ovate to ovate-lanceolate, concave and often somewhat cucullate, (0.35--)0.5--0.9(--1.5) mm long, margins plane to weakly recurved, often only at mid-leaf, and entire to, rarely, weakly toothed distally, apices obtuse; most costae ending before apex; medial laminal cells (9--)12--16(--22) µm, thin-walled to somewhat thickened. Seta (0.9--)1.5(--2.5) cm, red. Capsule ovate-cylindrical to, occasionally, ovate, (0.9--)1--1.2(--1.5) mm long, strongly sulcate when dry; peristome segments free at their nodes, finely papillose, dark red with pale borders to, rarely, completely pale. Spores (18--)19--21(--22)µm.

Capsules mature early summer--late fall. Sandy, usually moist soil, Arctic habitats; 0--200 m; Greenland; N.W.T. (Prince Patrick Island), w Yukon; c. Alaska; Eurasia.

This taxon has also been treated as a forma (C. purpureus f. heterophyllus (Kindberg) Britton); R. R. Ireland (1980) considered C. heterophyllus to be a variety of C. purpureus, but J. S. Burley and N. M. Pritchard (1990) provide ample evidence that this is a distinct species. The broadly ovate leaves of Ceratodon heterophyllus grade into some alpine variations of C. purpureus.