Monographs Details: Pterigynandrum
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)
Description:Genus Description - Plants very slender to medium-sized, in green, yellow-green or brownish, loose or dense, often ± shiny mats. Stems creeping or curved-ascending, freely and irregularly branched, in section showing 1-2 layers of smallish, ± thick-walled cells surrounding 5-10 large, ± thin-walled cells (central strand none); pseudoparaphyllia filamentous and paraphyllia none. Brood bodies sometimes produced in leaf axils, small, stalked, ovoid, golden-brown, 2-3-celled. Stem and branch leaves not differentiated, erect or imbricate, occasionally indistinctly homomallous, concave, elliptic to oblong-ovate or ovate, obtuse or more commonly acute, shortly decurrent; margins plane to reflexed or narrowly recurved in the lower half, serrulate above; costa short and double and sometimes ending just above the leaf middle, but usually shorter, commonly with 1 fork longer than the other, sometimes single and ending near the midleaf; upper cells rhomboidal to oblong-hexagonal, straight to distinctly flexuose, ± thick-walled, papillose at back because of prominent, almost bulbous papillae at the ends (often at lower as well as upper ends); alar cells quadrate to subquadrate (and wider than long) in small, triangular groups not reaching the costa; the non-quadrate cells across the insertion usually yellow, ± thick-walled, sometimes porose (in larger specimens), those of the decurrencies similar to the alar cells or more elongate. Dioicous. Perigonia small, bulbiform, in clusters (usually of 3) on old stems; bracts concave-tubulose, ovate, acute, ecostate; margins plane to slightly recurved and serrulate; cells long-rhomboidal to linear, flexuose, smooth. Perichaetia usually single on old stems; leaves pale, erect, concave-tubulose, oblong-lanceolate, gradually acuminate, ecostate; margins plane and serrulate above; cells linear-hexagonal, slightly flexuose, smooth. Setae elongate, smooth, twisted; capsules horizontal, curved-cylindric; exothecial cells short-rectangular, becoming quadrate toward the mouth; annulus of 2-3 rows of enlarged, thick-walled cells, deciduous (though sometimes remaining attached to the operculum); operculum conic-rostrate; exostome teeth attached at or below the mouth, ± hyaline (especially above), relatively short, lanceolate, often blunt, scarcely bordered, on the front surface with a straight median line and broad plates, smooth to papillose or irregularly striolate below, smooth from the middle upward, on the back with broad, unornamented plates, non-perforate, with not or only slightly projecting trabeculae; endostome ± hyaline, smooth, with a very low basal membrane, segments narrow, flat, very short to nearly as long as the teeth, cilia none. Spores spherical, finely papillose, ca. 12 µm.