7. Plagiothecium laetum Schimp. in B.S.G. 光泽棉藓 guang ze mian xian
Bryol. Eur. 5: 185. 1852. Leskea laeta (Schimp.) Berggr., Acta Univ. Lund. 2 Afd. 3(7): 8. 1866. Plagiothecium denticulatum var. laetum (Schimp.) Lindb., Not. Sällsk. Fauna Fl. Fenn. Förh. 9: 31. 1868. Plagiothecium denticulatum subsp. laetum (Schimp.) Kindb., Bih. Kongl. Svenska Vetensk.-Akad. Handl. 7(9): 46. 1883. Type: Switzerland.
Plants small, pale green or yellowish green, glossy, in loose mats. Stems prostrate, to ca. 2.0 cm long; leafy stems and branches complanate or slightly julaceous. All leaves more or less imbricate, distantly spaced, erect-spreading, often undulate, sometimes secund, usually asymmetric, narrowly ovate-lanceolate, 0.7–1.7 mm × 0.3–1.2 mm, gradually acuminate at apex; margins plane or narrowly reflexed near apex, usually entire, or serrulate near apex; costae short, double; median leaf cells linear-rhomboidal, 90–160 µm × 4–10 µm; basal cells rectangular, porose; alar regions decurrent, in a triangular shape, consisting of 1–3 rows of rectangular cells. Brood bodies present, often consisting of 3–6-celled gemmae. Autoicous. Setae 10–16 mm long, orange, brownish, or somewhat reddish; capsules erect or inclined, 1.5–2.0 mm long, smooth when dry; opercula 0.3–0.8 mm long; annuli deciduous; cilia 1–3, sometimes absent.