32. Tortula Hedw., Sp. Musc. Frond. 1801.
Plants small, stout, bright to dark green above, reddish brown below, in loose or dense tufts. Stems erect, simple, rarely irregularly branched, radiculose below; central strand present. Leaves contorted-curved or somewhat crisped when dry, spreading or slightly reflexed when moist, oblong-ligulate, obovate or spathulate, rounded-obtuse to broadly acute or mucronate at apex, sometimes sheathing at base; margins often recurved or revolute, entire or crenulate by projecting papillae, occasionally weakly serrulate near apex, borders sometimes differentiated by short or elongate, yellowish or brownish cells; costa stout or slender, reddish brown, usually excurrent, ending in a short to rather long, serrate or smooth awn, dentate on the dorsal surface and tips, in cross section 1 dorsal stereid band present, dorsal epidermal cells developed, rarely costa ending just below the apex; upper leaf cells often rounded-quadrate to hexagonal, thin- to moderately thick-walled, each cell covered by several C-shaped or circular papillae, rarely smooth; basal cells sharply differentiated, rectangular, hyaline, smooth. Autoicous or dioicous. Setae elongate, straight; capsules erect or slightly inclined, cylindrical; peristome teeth 32, filiform, or irregularly linear-lanceolate, twisted or sometimes erect, densely papillose, with low or high basal membrane; annuli weakly differentiated or consisting of 1–3 rows of vesiculose cells; opercula conic-rostrate, with a long oblique beak. Calyptrae cucullate, smooth. Spores spherical, small, yellowish or yellowish brown, smooth or minutely papillose.
With the segregation of Syntrichia, Tortula consists of seven species and one variety from China. Tortula bidentata X.-L. Bai was recently described from Nei Mongol, China (X.-L. Bai 1997). The species was considered to be closely related to Tortula desertorum Broth. (= Syntrichia caninervis Mitt.), and it is not treated here.