Plants 2--5 cm. Stem leaves 1.5--3 mm, linear-lanceolate; margins entire, plane; basal laminal cells thick-walled, yellowish; distal laminal cells 5--9 µm wide, opaque, lightly obscured by numerous tiny elliptic cuticular papillae. Sexual condition dioicous. Perichaetial leaves subsheathing at base, elongate, narrow, long-pointed. Seta 2.2--3.5 mm. Capsule barely exserted, 1--1.5 mm. Operculum rostrate. Spores 9--12 µm.

Seasonally wet crevices of neutral to acidic cliffs; 10--1500 m; Greenland; B.C., N.B., Nfld., N.W.T., N.S., Nun., Ont., Que., Yukon; Ala., Alaska, Calif., Colo., Conn., Ga., Idaho, Ky., Maine, Minn., Mont., N.H., N.Y., N.C., Ohio, Oreg., Pa., S.Dak., Tenn., Vt., Va., Wash., W.Va.; Europe; Asia.

This species has linear, entire leaves and small leaf cells (5--9 µm). The cuticular papillae are numerous, elliptic, and only lightly obscure the distal cells, whereas in A. lapponicum they are larger, warty, and much more noticeable.