Monographs Details: Racomitrium
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part One: Sphagnales to Bryales. Mem. New York Bot. Gard. 69 (1)
Description:Species Description - Plants fairly robust, in dull, often ± hoary, extensive mats. Stems creeping or more crowded and ascending, freely branched, sometimes with an abundance of short, tuftlike branches in a pinnate arrangement. Leaves erect or spreading, oblong-lanceolate, acute to acuminate and often hair-pointed, rarely blunt or rounded at the apex; costa ending below the apex to excurrent; cells sometimes bistratose toward the apex or at the upper margins, with thick and strongly nodulose walls below, sometimes also above, the upper cells usually short, smooth or papillose, the mid-basal cells long-linear, and the basal marginal cells short and straight-walled in 1 to several rows. Dioicous. Inflorescences lateral. Setae elongate; capsules erect and symmetric, oblong-ovoid, ellipsoidal, or oblong-cylindric, smooth, wrinkled, or obscurely plicate; annulus well differentiated; operculum long-rostrate; peristome teeth erect, ± completely split to the middle or nearly to the base into 2 terete, sometimes filiform, papillose segments; preperistome present as a low, smooth, hyahne membrane adhering to the base of the teeth. Spores spherical. Calyptrae conic-mitrate, often rough above, not hairy or plicate.
The strongly nodose cell walls of the leaf base and usually also the upper leaf are significant features of the genus, although suggestions of the same thickenings can be seen in Grimmia, especially at leaf bases. The pleurocarpous manner of growth and the long, terete divisions of the peristome also have generic importance.