2. Dicranodontium asperulum (Mitten) Brotherus in H. G. A. Engler and K. Prantl, Nat. Pflanzenfam. 208 [I,3]: 336. 1901.
Dicranum asperulum Mitten, J. Linn. Soc., Bot., suppl. 1: 22. 1859; Campylopus virginicus (Austin) Lesquereux & James; Dicranum virginicum Austin
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, channeled distally, margins serrulate to serrate at shoulders, usually strongly serrate distally, apex acute; costa distinct, occupying ca. 1/3 of leaf base; cells not thick-walled or pitted, distal cells linear, 24-56 × 5-6 µm, 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 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 of Dicranodontium asperulum were seen in North America only in one British Columbia specimen. 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 D. asperulum the most distinctive North American species of the genus. The leaves of the other species are appressed or weakly spreading when wet, with entire bases.