Epipterygium
Öfvers. Kongl. Svenska Vetensk.-Akad. Förh. 19: 603. 1863.
Plants small to medium-sized, as loose turfs or scattered plants. Stems 0.1–1 cm, slightly complanate-foliate, often bearing subfloral innovations below the gametangia. Leaves with dorsal leaves in 1–3 rows, smaller than lateral leaves, all leaves spreading, ovate-lanceolate to elliptic, 0.4–1.5[–2.5] mm; base slightly decurrent; margins plane, weakly serrulate in distal 1/3; apex ± abruptly acute; costa ending well before apex; distal medial laminal cells broadly rhomboidal; marginal cells weakly but distinctly [to strongly] differentiated from medial cells. Specialized asexual reproduction absent. Sexual condition dioicous; perigonia and perichaetia terminal; perigonial leaf apex short- to ± long-acuminate; outer perichaetial leaves slightly larger, inner leaves slightly smaller than vegetative leaves, somewhat differentiated, lanceolate. Seta single, orange-brown, bent near apex. Capsule pendulous, inclined 160–180°, narrowly cylindric, short-pyriform, or urceolate, 1–3 mm, neck short; exothecial cells near mouth in 2 or 3 rows, medial cell walls strongly collenchymatous; stomata superficial; annulus revoluble; operculum long-conic; peristome double, 4:2:6–8; exostome yellow to light brown, teeth triangular-acute, trabeculate, pitted basally, coarsely or finely papillose distally; endostome basal membrane high, segments wide, strongly keeled, broadly perforate, cilia 1–3.
Distribution
North America, Mexico, Central America, South America, Europe, Asia, Pacific Islands (New Zealand).
Discussion
Species ca. 12 (1 in the flora).
Epipterygium is a small genus of tropical and temperate mosses similar in morphology to Pohlia, generally distinguished by more or less complanate foliation in which two or three rows of larger lateral leaves are differentiated in size and shape from one to three rows of smaller, narrower dorsal leaves. The degree of leaf dimorphism reaches an extreme in E. wrightii (Sullivant) Lindberg of the Caribbean region, but the only North American species, E. tozeri, is almost uniformly foliate and scarcely complanate. This species is especially similar to Pohlia, and phylogenetic analyses corroborate a close relationship between the two genera.