3. Thuidium delicatulum (Hedw.) Schimp. 细枝羽藓 xi-zhi yu xian
Bryol. Eur. 5: 164 (fasc. 49–51. Monogr. 8). 1852. Thuidium delicatulum (Hedw.) Mitt., J. Linn. Soc. Bot. 12: 578. 1869, hom. illeg. Hypnum delicatulum Hedw., Sp. Musc. Frond. 250. 1801. Type. U.S.A.
Thuidium uliginosum Card., Bull. Soc. Bot. Genève, ser. 2, 3: 283. 1911.
Thuidium viride Mitt., Trans. Linn. Soc. London, Bot. 3: 188. 1891.
Plants large, up to 12 cm long, yellowish green to lightly brownish green, in large interwoven mats. Stems regularly tripinnately branched; branches 5–15 mm long; central strand present; paraphyllia dense on stems and branches, foliose or filamentous, branched and papillose. Stem leaves about 1 mm long, triangularly ovate, slightly plicate, concave, suddenly narrowed into a lanceolate acumen, often secund; margins serrate; costa reaching near leaf apex, multipapillose on back; median leaf cells oblong to rounded-rhomboidal, ca. 6–15 µm wide, thin-walled, unipapillose; branch leaves concave, usually ovate, with short apices; costa up to 4/5 the leaf length. Dioicous. Perichaetial leaves ovate-lanceolate, usually long ciliate at shoulder, rarely entire. Setae reddish brown, 3 cm long, smooth; capsules cylindrical, curved; exostome teeth reddish brown, grossly papillose above; endostome segments as long as the teeth, finely papillose above; lightly yellowish; basal membrane about 1/2 the height of segments; cilia 2–3, finely papillose. Spores about 20 µm in diameter, finely papillose.