Syntrichia caninervis Mitten 1859

Syntrichia caninervis is most common in the colder deserts and steppes of the flora area, particularly in the Mojave and Great Basin deserts and the Columbia Basin. It can be confused in the field with S. ruralis, but good field distinctions for S. caninervis include the blackish or olive green color, the imbricate, weakly twisted leaf stance when dry, and the back of the costa showing no trace of red and often having a frosty appearance because of the stellate papillae. Microscopically, S. caninervis is unique with its combination of 2-stratose laminae, non-bulging cell surfaces, and costal cross-sections with sub-stereid cells.

Stems 3-20 mm. Leaves infolded and imbricate, not to weakly twisted around stem when dry, erect-spreading when moist, ovate-spatulate, 1-2.5 × 0.6-1.2 mm, 2-stratose or thicker, occa-sionally with scattered 1-stratose patches; margins revolute for the entire length of leaf, entire; apices acute to acuminate; costa excurrent into a serrate, hyaline awn that is often broadly hyaline at base, brown or blackish, strongly papillose; basal cells abruptly differentiated, narrower toward the margins; distal cells rounded, polygonal, or quadrate, 8-13 µm, with 4-6 low papillae per cell. Specialized asexual reproduction absent. Sexual condition dioicous. Seta 6-15 mm, brown. Capsule red, 2.5-3.2 mm, straight or slightly curved, with a distinct neck; operculum 1.5-2mm, red; peristome 0.7-1 mm, the basal membrane about ¹/2 the total length. Spores 7-8 µm, lightly papillose.

Plants small to medium-sized, to 1.5(–2.0) cm high, in dense tufts. Stems erect, usually simple; central strand present. Leaves appressed to contorted-curved when dry, spreading or somewhat reflexed when moist, oblong-ligulate to spathulate, rounded-obtuse at apex, upper lamina broadly channeled or keeled, weakly sheathing at base; margins strongly revolute, crenulate by projecting papillae; costa rather stout, often reddish brown, excurrent, ending in a rather long awn, often serrulate on the back and at tips; upper leaf cells subquadrate to hexagonal, more or less thin-walled, each cell densely covered with several C-shaped papillae; basal cells distinctly differentiated, rectangular, thin-walled, hyaline, smooth. Autoicous. Setae ca. 1 cm long, straight; capsules erect, cylindrical; opercula conic-rostrate, with a long oblique beak.

Distribution: China, Mongolia, Russia (Siberia), central and southwestern Asia, Europe, and North America.

Habitat: on rocks or soil; also on grassland.

Tortula bistratosa Flowers; T. caninervis (Mitten) Brotherus

Barbula caninervis (Mitt.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1871–72: 453 (Gen. Sp. Musc. 1: 301). 1873. Tortula caninervis (Mitt.) Broth., Nat. Pflanzenfam. I(3): 435. 1902. Grimmia cucullata J.-X. Luo & P.-C. Wu, Acta Phytotax. Sin. 18: 121. f. 2: 1–7. 1980, hom. illeg. Syntrichia desertorum (Broth.) Amann, Fl. Mouss. Suisse 3: 39. 1933. Barbula desertorum (Broth.) Par., Index Bryol. 71. 1894. Tortula desertorum Broth., Beih. Bot. Centralbl. 34: 24. 1888.