Syntrichia fragilis Ochyra 1992

Syntrichia fragilis shows considerable variability in size and leaf shape (apparently correlated with habitat conditions). In some small, corticolous plants, extreme fragmentation is evident, with an abnormal development of the lamina beyond the usual outline of the leaf. In such plants, several regions of each leaf seem to remain meristematic and produce scalloped or ruffled extensions that eventually break off. Fragility of leaves should not be considered an infallibly diagnostic character, however, since some plants of S. fragilis have quite firm leaves, and the leaves of some other species, particularly when old, may become broken.

Stems (5-)10-25 mm. Leaves crowded, longitudinally folded and spirally twisted around the stem (but little crisped) when dry, wide-spreading when moist, oblong-lingulate to spatulate, 2-3.5 × 0.75-1 mm, fragile, with sheets of cells breaking off, sometimes along lines of weakness; margins revolute before to as much as ¹/2 the leaf length, to plane, entire or crenulate; apices truncate to acute; costa percurrent or slightly excurrent as a mucro 1-3(-5) cells long, yellow or red, finely to strongly papillose abaxially, abruptly tapered; basal cells abruptly differentiated, becoming rather abruptly short-rectangular near the margins; distal cells quadrate-hexagonal, 9-15 µm, bulging, with 3-8 papillae per cell, with moderately thick walls, not particularly collenchymatous; distal marginal cells not or weakly to strongly differentiated as a border of brownish, thicker-walled cells in about 2-3 rows. Specialized asexual reproduction absent. Sexual condition dioicous. Seta red, 10-15 mm. Capsule red, (1.5-)2-4 mm, slightly curved, rather gradually tapered to the seta or with a distinct neck; operculum 1-1.5 mm, red; peristome 1-1.5 mm, teeth twisted about ¹/2 turn, the distal divisions yellow, the basal membrane pale, about ¹/4 the total length. Spores 13-20 µm, densely papillose.

Plants small, but rather thick, to 1.2 cm high, dark green to reddish brown, in loose tufts. Stems erect, simple, radiculose at base; central strand present. Leaves contorted-curved when dry, spreading when moist, oblong-ligulate to spathulate, rounded-obtuse to abruptly acute or mucronate at apex; margins often recurved, crenulate by projecting papillae; costa stout or rather slender, percurrent, often reddish brown, smooth on the dorsal surface; upper leaf cells subquadrate to rounded-hexagonal, green, each cell densely covered with several C-shaped papillae; basal cells distinctly differentiated, rectangular, thin-walled, hyaline, smooth. Autoicous. Setae elongate, 4–6 mm long, yellowish brown; capsules erect or slightly inclined, cylindrical; peristome teeth 32, linear or filiform, twisted, papillose; basal membrane high.

Distribution: China, central and western Asia, Europe, and North America.

Habitat: on rocks in shade or on forest ground.

Tortula fragilis Taylor, London J. Bot. 6: 333. 1847

Barbula fragilis (Tayl.) C. Müll., Syn. Musc. Frond. 1: 634. 1849. Syntrichia schmidii (C. Müll.) Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 39. 1859. Tortula schmidii (C. Müll.) Broth., Nat. Pflanzenfam. I(3): 434. 1902. Barbula schmidii C. Müll., Bot. Zeitung (Berlin) 11: 58. 1853.