Great Hairy Screw Moss

Syntrichia ruralis generally has conspicuously squarrose-recurved leaves when wet, with margins recurved nearly to the apex, distal portions of the costa toothed abaxially because of projecting cell ends, and relatively small laminal cells. The decurrent, hyaline base of the awn sometimes used to distinguish S. ruraliformis is not reliable and can, on occasion, be found in S. princeps, S. papillosissima, and S. norvegica. Specific distinctions in the S. ruralis complex are subtle, for the most part, requiring cross sections of leaves and stems, and careful measurements. The leaves of S. princeps and S. obtusissima are narrowed near the middle, whereas those of S. papillosissima, S. norvegica, and S. ruralis are widest about one-third the way up from the base and then taper to the apex. The stem of S. princeps and S. obtusissima has a strong central strand of thinner-walled cells, the costa has a group of hydroids just abaxial to the guide cells, and the basal cells in the leaf are relatively wide. In S. papillosissima, S. norvegica, and S. ruralis, the stem lacks a central strand, the costa lacks hydroids, and the basal cells in the leaf are relatively narrow.

Stems 5-15 mm. Leaves clasping at base, infolded and twisted around the stem when dry, wide-spreading (in smaller forms) to squarrose-recurved when moist, lingulate-ovate, 1.5-3.5 × 0.75-1.25 mm, canaliculate to keeled; margins tightly revolute in the proximal ⁷/8 or more, entire; apices emarginate to acute; costa excurrent into a serrate (or occasionally only faintly serrulate), hyaline awn that is often red or sometimes broadly hyaline at base, weakly to strongly papillose on the abaxial surface and often serrate near the apex because of projecting cell ends, red-brown; basal cells abruptly differentiated, narrowly rectangular, 35-70(-90) × 11-18 µm, quadrate to narrowly rectangular at the margins; distal cells quadrate to polygonal, 8-12 µm, with 3-6 papillae per cell, bulging, somewhat obscure. Specialized asexual reproduction absent. Sexual condition dioicous. Seta red, 5-10 mm. Capsule red-brown, 2-3.5 mm, straight, with an abrupt neck; operculum 1.25-1.75 mm, brown; peristome ca. 1.25 mm, the upper divisions twisted ca. 2 turns, red, the basal membrane white, about ¹/3 the total length. Spores 11-15 µm, papillose.

Plants large to rather robust, 5.0–8.0 cm high, dark green to reddish brown, in loose tufts. Stems erect, simple or irregularly branched, radiculose at base; central strand absent. Leaves appressed or erecto-patent to contorted-curved when dry, spreading or sometimes reflexed when moist, oblong-spathulate, rounded-obtuse to broadly acute at apex, upper lamina broadly channeled or keeled, sheathing at base; margins often recurved, crenulate by projecting papillae; costa rather stout, often reddish brown below, excurrent, ending in a rather long, hyaline awn, denticulate on the back or at tips; upper leaf cells subquadrate to rounded-hexagonal, each cell densely covered with several C-shaped papillae; basal cells distinctly differentiated, narrowly rectangular, thin-walled, hyaline, smooth. Dioicous. Setae elongate, straight, 1–2 cm long, reddish brown; capsules erect, cylindrical; peristome teeth filiform, twisted, papillose; basal membrane high, 1/2 –1/3 the peristome teeth length; annuli differentiated, of 2–3 rows of vesiculose cells, deciduous; opercula conic-rostrate, with a long oblique beak.

Distribution: China, India, northern Africa, Europe, Russia, North and South America, and Australia.

Habitat: on forest ground, rocks, or soil in shade.

Barbula ruralis Hedwig, Sp. Musc. Frond., 121. 1801; Syntrichia ruraliformis (Bescherelle) Dixon; Tortula ruraliformis (Bescherelle) W. Ingham; T. ruralis (Hedwig) P. Gaertner, B. Meyer & Scherbius

Tortula ruralis (Hedw.) Gaertn., Oekon. Fl. Wetterau 3(2): 91. 1802. Tortula reflexa X.-J. Li, Acta Bot. Yunnan. 3: 109, f. 6. 1981, hom. illeg. Type. China. Xizang, Ding-qing Co., M. Zang 5340a (holotype HKAS).

Syntrichia ruralis, commonly known as twisted moss and star moss, is a species of moss with a cosmopolitan distribution. It occurs in North America, the Pacific, Europe, Asia, the Middle East, North and South Africa, South America, and Australia. It grows in many types of climate, including the Arctic, boreal areas, temperate areas, and deserts. It grows in tundra, coniferous forest, grassland, sagebrush steppe, and other habitat types.

This moss forms tufts of erect stems up to 4 centimeters tall. When it is wet it is bright green and the leaves are loose. When it dries the leaves wrap around the stem and it becomes reddish brown in color. It is dioecious. It also performs vegetative reproduction.

Though it occurs in many types of habitat, it is usually not a dominant species. The moss grows on many types of soil, but most often calcareous soils. It tolerates a variety of elevations and levels of sunlight. It may be a component in cryptogamic crusts. It helps to stabilize soil and reduce erosion. It can dry out and become dormant for many years, becoming metabolically active again after many decades of desiccation. It is used as a model organism in studies of desiccation.

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