Hypnum tectorum Funck ex Bridel, Bryol. Univ. 2: 582. 1827; Pseudoleskea tectorum (Funck ex Bridel) Schimper

Plants dark olive green or rarely yellow-green. Stems tightly appressed to substrate, branches appressed. Stem leaves ± catenulate when dry, not homomallous, ovate, abruptly narrowed to apex, concave, not plicate, 0.4-1.2 mm, 1.5-2:1; base flaring; margins plane or rarely recurved proximally, entire; apex short-acuminate, sometimes falcate; costa usually double, or single, 2-fid, or sometimes ecostate, weak, not reaching mid leaf; medial laminal cells 1-2(-3):1, walls firm, not incrassate. Branch leaves ovate to suborbicular, 0.4-0.8 mm; laminal cell walls moderately incrassate. Stoloniferous leaves broadly ovate or suborbicular. Seta red-brown, 0.1-0.2 cm. Capsule inclined, subcylindric, asymmetric, 1.5-2.5(-3) mm. Spores 10-18 µm.

Capsules mature summer. Shaded calcareous rock, shaded tree bases or wood; low to high elevations (0-4000 m); Greenland; Alta., B.C., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Sask.; Alaska, Ariz., Calif., Colo., Idaho, Kans., Mich., Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wyo.; Eurasia.

Pseudoleskeella tectorum distinguished by the dark green, tightly appressed, catenulate leaves, and weak costa. Thin mats of this species can be become quite extensive over time, covering the faces and overhangs of shaded boulders and cliffs.