Leskea smithii Swartz in S. Liljeblad, Utkast Sv. Fl. ed. 3, 549. 1816; Calliergon arcticum (Sommerfelt) Kindberg; Hypnum torrentis Müller Hal. & Kindberg; Ochyraea smithii (Swartz) Ignatov & Ignatova

Plants very coarse and stiff, dark green, olive green, or black, all with or without golden green or golden brown mottling. Stems to 8 cm, denuded proximally or with persistent, shredded bases, unbranched or irregularly branched; hyalodermis absent, epidermal cells small, walls thick, similar to subadjacent cortical cells, central strand well developed. Leaves stiffly and loosely imbricate to erect-spreading, straight, sometimes secund, shrinking and twisting when dry, spreading when moist, usually broadly ovate, elliptic, or orbicular, sometimes ovate, transverse, or triangular, plane or shallowly concave, (0.6-)0.8-1.2(-1.5) × (0.4-)0.6-1.2(-1.4) mm; margins plane, entire or weakly denticulate; apex usually obtuse or rounded; costa stout, single to 3/4 leaf length, often 2-fid, occasionally double and short; alar cells few, quadrate to rectangular, region not clearly differentiated; basal laminal cells usually longer, wider than medial cells, ; medial cells rhomboid, fusiform to short-fusiform, or linear-flexuose, 22-48(-64) × (4-)5-7(-10) µm; apical cells rhombic or rounded; marginal cells often in ill-defined border of short cells. Sexual condition autoicous; ; perichaetial inner leaves lanceolate, . Seta red or brown, 0.8-1.7 cm. Capsule with endostome cilia 1-3.

Irrigated to emergent acidic rock in montane streams, rock, wood, in slow moving water or ponds; moderate to high elevations (500-3100 m); Greenland; Alta., B.C., Nfld. and Labr., N.S., Que.; Alaska, Calif., Colo., Mont., Wash.; Europe; Atlantic Islands (Iceland).

Hygrohypnum smithii is a well-defined species, easily recognizable by the coarse, rigid habit, usually broadly ovate to orbicular leaves, and stout, usually single costa. The alar cells have incrassate, yellowing walls.