Plants brown proximally, yellowish to dark green distally, dull to glossy, in loose tufts. Stems 1--6(--8) cm, radiculose proximally with whitish to reddish brown rhizoids. Leaves erect-patent, flexuose, spreading at ca. 45º or more when wet, occasionally falcate-secund at stem apices, 3--8 mm, often deciduous, abruptly narrowed from an ovate base into a setaceous subula, subtubulose proximally, channelled distally, margins serrulate to serrate at shoulders, usually strongly serrate distally, apex acute; costa distinct, occupying ca. 1/3 of leaf 5--6 μm,base; cells not thick-walled or pitted, distal cells linear, 24--56 basal cells broadly rectangular, hyaline, ca. 9 μm wide, alar cells sometimes forming indistinct auricles, hyaline. Seta 15--20 mm, erect-sinuose. Capsule 1.5--2.0 mm; operculum not seen, reportedly shorter than the capsule. Spores 9--14 μm.

Damp, shaded, acidic cliff faces and cliff shelves, occasionally on earth of overturned tree roots; 0--1200 m; B.C.; Alaska, Ga., Ky., N.C., Tenn., Va., W.Va.; Europe; Asia.

Sporophytes seen in North America only from one British Columbia specimen. H. A. Crum and L. E. Anderson (1981) reported the sporophyte described by E. G. Britton in Dicranodontium virginicus with spores maturing in summer. The spore size was given by A. J. E. Smith (1978) for plants in Britain and Ireland. The wide-spreading leaves, standing out from the stem at 45° or more when wet, and the serrate to serrulate shoulders of the leaf bases make Dicranodontium asperulum the most distinctive of the North American Dicranodontium species. The leaves of the other species are appressed or weakly spreading when wet, with entire bases.