3. Plagiothecium denticulatum (Hedw.) Schimp. in B.S.G. 棉藓 mian xian
Bryol. Eur. 5: 190. 1851. Stereodon denticulatus (Hedw.) Mitt., J. Proc. Linn. Soc., Bot. 7: 158. 1863. Hypnum denticulatum Hedw., Sp. Musc. Frond. 237. 1801. Type: Germany.
Plagiothecium denticulatum fo. undulatum (R. Ruthe ex Geh.) C. E. O. Jensen, Skand. Bladmossfl. 494. 1939. Plagiothecium denticulatum var. undulatum R. Ruthe ex Geh., Rev. Bryol. 4: 42. 1877.
3a. Plagiothecium denticulatum var. denticulatum 棉藓原变种 mian xian yuan bian zhong
soft, rather large, green to yellowish green, sometimes dark green, often glossy, in loose or dense mats. Stems
prostrate or ascending, usually longer than 5 cm, complanate, irregularly branched, densely foliate;
stem elliptical in cross section, ca. 0.3–0.5 mm in diameter; central strand not clearly differentiated. All leaves complanate, often slightly concave, mostly asymmetric, shortly ovate-lanceolate, 1.0–2.0 mm × 0.6–0.9 mm, gradually or abruptly narrowed to a short, often acute apex; margins entire below, serrulate near apex, sometimes reflexed on one side below; costae slender, short, double or forked, rarely reaching to the mid-leaf; median leaf cells linear-rhomboidal, 80–120 µm × 10–15 µm; apical cells short; basal cells broader, short, ca. 25 µm long, more or less porose; alar regions broadly decurrent, consisting of shortly rectangular or rounded-quadrate, inflated cells. Brood bodies often present in leaf axils. Autoicous or dioicous. Perichaetial leaves shortly ovate-lanceolate, abruptly narrowed to a short apex. Setae 12–22 mm long, reddish brown; capsules inclined to horizontal, curved, shrunken when dry, ca. 2.0 mm long with operculum; opercula conic-rostrate with a short beak; annuli well developed; stomata at neck; peristome typical for the genus; cilia 2, nodulose. Spores 10–13 µm in diameter, minutely papillose or nearly smooth.