纽藓属

Plants small to medium-sized, sometimes rather large, to 6 cm high, green to dark green or reddish brown, in loose or dense tufts. Stems erect, simple or branched; central strand absent or weak to strong. Leaves often crowded, appressed or contorted-curved to strongly crisped when dry, spreading or reflexed when moist, ligulate to oblong or linear-lanceolate or oblong-lanceolate, often channeled above, narrowly to broadly acute, somewhat sheathing at base; margins plane or somewhat undulate or narrowly incurved, entire to weakly serrulate or crenulate with projecting papillae; costa subpercurrent to percurrent or excurrent as a short awn; in cross section 2 stereid bands present; upper leaf cells quadrate to hexagonal, green, often unistratose, sometimes bistratose, pluripapillose, with either branched or simple papillae; basal cells often sharply differentiated, rectangular, smooth, forming a V-shaped base. Dioicous or autoicous. Setae slender, yellowish to reddish brown; capsules erect or slightly inclined, oblong-ovoid to cylindric; peristome teeth 32, linear to filiform, often twisted counterclockwise, densely papillose; basal membrane low or absent; annuli differentiated, of 1–4 rows of vesiculose cells; opercula long conic-rostrate. Calyptrae cucullate, smooth. Spores spherical, yellowish brown, smooth or papillose.

Three species of Tortella are recognized in China. Tortela inflexa (Bruch) Broth. reported from Zhejiang (Wilson 1848) and T. nitida (Lindb.) Broth. from Xinjiang (B.-C. Tan, J.-C. Zhao & R.-L. Hu 1995) cannot be confirmed by this study.

Lower Taxa

• Tortella fragilis (Hook. & Wils.) Limpr.
• Tortella humilis (Hedw.) Jenn.
• Tortella tortuosa (Hedw.) Limpr.