6. Schistidium Bruch & Schimp. in B.S.G. 连轴藓属 lian-zhou xian shu
Bryol. Eur. 3: 93 (fasc. 25–28). 1845, nom. cons. Lectotype species: Schistidium maritimum (Turn.) Bruch & Schimp. in B.S.G. (Grimmia maritima Turn., typ. cons.) [Homonym: Schistidium Brid., Muscol. Recent. Suppl. 20. 1819, rejected against Schistidium Bruch & Schimp., proposed by Ochrya & Isoviita (1989), Taxon 38: 665–669. Type: Schistidium pulvinatum (Hedw.) Brid. (Gymnostomum pulvinatum Hedw.)]
Grimmia subgen. Schistidium (Brid.) Schimp., Coroll. Bryol. Eur. 45. 1856. Grimmia sect. Schistidium (Brid.) Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 43. 1859.
Plants slender to robust, green to yellowish green, reddish brown or black, in loose tufts. Stems erect to prostrate, frequently branched from innovations, with or without central strand in cross section. Leaves imbricate, erect when dry, erect-spreading to spreading when moist, lanceolate, ovate to ovate-lanceolate, keeled or obtusely keeled above, muticous or ending in short to long, hyaline hair-points; margins recurved on one or both sides, sometimes bistratose above; costa strong, single, percurrent or ending below the apex, terete, smooth or papillose on abaxial surface, consisting of nearly homogeneous cells in transverse section; upper cells quadrate to irregularly quadrate, unistratose or bistratose in places, with more or less thick, straight to sinouse walls, smooth; basal cells short, transversely rectangular to quadrate, occasionally short-rectangular to rectangular, with somewhat sinuose walls. Autoicous (except S. tenerum). Perichaetial leaves much larger than vegetative leaves, with broad base, loosely areolate. Setae straight, shorter than capsule urns, erect when dry; capsules erect, immersed in perichaetial leaves, subglobose to oblong-ovoid, smooth or nearly so; exothecial cells transversely rectangular to quadrate or rectangular, with thick or thin walls; stomata restricted to base of urns; annuli absent; opercula low-conic, with short, more or less oblique beaks; columella falling attached with opercula; peristome teeth 16, haplolepideous, well developed or vestigial, yellowish brown to reddish brown, erect, lanceolate to linear-lanceolate, entire or imperfectly perforate and split above, papillose on both outer and inner surfaces, sometimes nearly smooth in basal part of outer surface, outer plates thicker than inner plates. Calyptrae rather small, not extending to urns, cucullate to mitrate. Spores small or large, 9–19 µm in diameter, yellowish green, smooth or papillose.