Monographs Details: Tortula ruralis (Hedw.) P.Gaertn., B.Mey. & Scherb.
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part One: Sphagnales to Bryales. Mem. New York Bot. Gard. 69 (1)
Description:Species Description - Plants small to robust, 5-15 mm high, in dense, red-brown to black tufts. Leaves clasping at base, infolded and twisted around the stem when dry, wide-spreading (in smaller forms) to squarrose-recurved when moist, 1.5-3.5 mm long, 0.75-1.25 mm wide, Ungulate-ovate, canahculate to keeled, emarginate to acute; margins tightly revolute in the lower 7/8 or more, entire; costa strong, red-brown, weakly to strongly papillose at back and often serrate near the apex because of projecting cell ends, excurrent into a serrate (or occasionally only faintly serrulate), hyaline hair point that is often red or sometimes broadly hyaline at base; upper cells 8-12 µm, quadrate to polygonal, somewhat obscure, bulging, with 3-6 papillae per cell; basal cells abruptly differentiated, narrowly rectangular, 35-70(-90) x 11-18 µm, quadrate to narrowly rectangular at the margins. Dioicous. Setae 5-10 mm long, red; capsules 2-3.5 mm long, straight, with an abrupt neck, red-brown; operculum 1.25-1.75 mm long, brown; peristome ca. 1.25 mm long, the upper divisions red, twisted ca. 2 turns, the basal membrane white, ca. 1/3 the total length. Spores 11-15 µm, papillose. Calyptrae 2.5-3.5 mm long, brown.
T. ruralis (Hedw.) Gaertn., Meyer & Scherb., Okon. Techn. Fl.
Barbula ruralis Hedw., Sp. Muse. 121. 1801.
Syntrichia intermedia Brid., Bryol. Univ. 1: 586. 1826.
Tortula intermedia (Brid.) De Not., Syll. 181. 1838.
T. ruralis var. crinita De Not., Mem. Reale Accad. Sci. Torino 40:291. 1838.
This extremely variable species generally has conspicuously squarrose-recurved leaves with margins recurved nearly to the apex, upper portions of the costa toothed at back because of projecting cell ends, and cells relatively small. Small plants from xeric habitats have been called T. intermedia or T. ruralis var. crinita. However, growth experiments (Mishler, 1985a and unpublished) s h o w that the size characteristics held by some to distinguish T. intermedia are extremely plastic with respect to light and temperature. Likewise the decurrent, hyahne base of the hair point sometimes used to distinguish T. ruraliformis (Besch.) Dix. is not reliable (Mishler, 1985a) and can, on occasion, be found in T. princeps, T. papillosissima, and T. norvegica. Specific distinctions in the Tortula ruralis complex are subtle, for the most part requiring cross-sections of leaves and stems and careful measurements. The leaves of T. princeps and T. obtusissima are narrowed near the middle, whereas those of T. papillosissima, T. norvegica, and T. ruralis are widest about one-third the w a y up from the base and then taper to the apex. T h e stem of T. princeps and T. obtusissima has a strong central strand of thinner-walled cells, and the costa has a group of hydroids just dorsal to the guide cells. In T. papillosissima, T. norvegica, and T. ruralis, the stem lacks a central strand and the costa lacks hydroids. Theme an size of upper leaf cells is in T. obtusissima 18 µm, in T. princeps, T. norvegica, and T. papillosissima 15, 14, and 13 µm, respectively, and in T. ruralis 10 µm. Theme an width of basal cells ranges from 31 µm in T. obtusissima to 25 µm in T. princeps, 18 µm in T. papillosissima and T. norvegica, and 15 µm in T. ruralis.
Collections from elevations above 3500 m on Cerro Potosi, Nuevo Leon (Norris 17644, 17645, TENN), and Sierra Coahuilon, Coahuila (Whittemore 2670, MEXU), have been recorded as T. percarnosa (C. Müll.) Broth., but they may be better referred to the Andean Tortula kingii Robins. The leaves suggest T. fragilis in outline, but they are weakly cucullate and not fragile, with smaller upper cells (8-10 µm) and relatively small basal cells. The identification of these specimens, illustrated in FIG. 261 as T. kingii, must await study of an Andean complex of cucullate-leaved species, including T. kingii, T. percarnosa, and T. nigra Zand. [This complex appears to be related to T. fragilis, but the information was received too late to insert in a more suitable position between T. fragilis and T. bogotensis.—Editors]
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