Bryologist 103: 513, figs. 2, 3. 2000.
Plants small to medium-sized, green or yellowish. Stems creeping, 1-pinnate or sometimes irregularly 2-pinnate; paraphyllia polymorphous, filiform or sometimes narrowly lanceolate, branched or sometimes unbranched, cells oblong, smooth or papillose over end walls, apical cell bluntly conic by wall thickened at tip; pseudoparaphyllia lanceolate or ovatelanceolate, margins ciliate or serrate, proximal cells subquadrate, centrally papillose. Stem-leaves spreading, broadly ovate or rarely elliptic; margins plane or recurved, spinose-serrate distally, entire or distantly serrulate in acumen; apex abruptly narrowed, acumen subulate; costa surface with coarse, spinose teeth over proximal 1/2; laminal cells with abaxial surface echinate, 1-papillose, papilla coarsely obliquely blunt-conic; medial cells subquadrate to short-rectangular; apical cell 20: 1, smooth. Branch leaves differentiated from stem-leaves, spreading or spreading-erect, slightly overlapping, ± catenulate when dry, broadly ovate, concave; apex abruptly acute; distal medial laminal cells irregular, rhombic, oblong, or subquadrate, walls incrassate; apical cell 7: 1, with distal bluntly conic wall thickening. Sexual condition dioicous; perichaetia inner leaves cilia present. Seta 2–2.8 cm. Capsule with stomata present in proximal 1/2. Spores 10–16 µm.
nw North America, e Asia