Monographs Details: Pinnatella
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 small and slender, dull, dark-green, or yellow. Secondary stems ± frondose above a stipitate base; branches blunt or tapered, rarely flagellate; paraphyllia none. Stipe leaves small, wide-spreading. Branch leaves spreading, not or loosely complanate, somewhat concave, generally biphcate, very rarely undulate, broadly ovate to somewhat lingulate, mostly broadly and bluntly pointed; margins plane, entire or serrulate at least above; costa generally ending just below the apex; cells small, thick-walled, rounded-quadrate to rounded-hexagonal or short-rhomboidal, smooth or minutely 1 (-3)-papillose, short throughout or ± elongate toward the base. Dioicous. Perichaetia small, with bracts often wide-spreading at the tips. Setae mostly 3-5 mm long, yellow, somewhat rough; capsules oval, becoming blackish; annulus not especially differentiated; operculum rather short; exostome teeth lanceolate, often perforate, densely papillose, trabeculate at back; endostome smooth or papillose, consisting of a low basal membrane, linear, keeled and narrowly perforate segments, and no cilia. Calyptrae unknown.
The small, more or less isodiametric leaf cells provide the most constant character difference from Porotrichum.