Bryol. Univ. 1: 380. 1826 ,.
Plants in dense cushions, yellow-green distally, brown and compacted with red-brown radicles proximally. Stems forked. Leaves erect-spreading, crisped when dry, lance-acuminate, keeled, ending in a sharp, hyaline cell or short point; margins 2-stratose and narrowly revolute nearly to the apex, entire or somewhat irregular; costa prominent at base, smooth, ending near the leaf apex, entire to shortly excurrent; distal cells irregularly rounded-quadrate, smooth, thick-walled; basal cells narrowly rectangular, thick-walled, the alar cells not differentiated. Sexual condition autoicous; perigonial buds minute, at base of perichaetium; perichaetial leaves similar to stem leaves, ending in a short, hyaline awn. Seta straight or somewhat curved when dry, cygneous when moist, yellow. Capsule mostly erect when dry, pendent when moist, short-necked, symmetric, subglobose but becoming broader at the mouth and somewhat contracted at the middle when dry, orange-brown, strongly ribbed; annulus persistent; operculum obliquely rostrate from a convex base; peristome teeth inserted slightly below the mouth, lance-acuminate, brown at base, entire or occasionally somewhat perforated, rarely cleft, yellowish brown above, pale at the slender tips, vertically striolate throughout. Calyptra cucullate, smooth. Spores warty-papillose, brown.
North America, Europe, Asia.
Oreas much resembles Cynodontium, but has a cygneous seta (when moist) and symmetric capsules. European specimens are more slender, with shorter leaves, but the differences are not significant.
Steere, W. C. 1958. The discovery of Oreas martiana in arctic Alaska, a genus new to North America. Bryologist 61: 119–124.