Monographs Details: Grimmia
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:Genus Description - Plants small to medium-sized, in yellow- to dark-green, brown, red-brown, or blackish cushions. Stems suberect, usually forked. Leaves concave or keeled, ovate to lanceolate or oblong-elliptic, often hair-pointed; margins often recurved on 1 or both sides, especially below, entire or rarely ± denticulate above, sometimes thickened; costa ending at or near the apex or excurrent into a hair point; upper cells short, usually thick-walled, sometimes ± sinuose, usually smooth, often bistratose, especially toward the apex; basal cells often elongate and often ± sinuose, usually subquadrate in the alar regions. Dioicous or autoicous. Sporophytes terminal but often appearing to be lateral because of subfloral innovation. Setae very short to ± elongate, sometimes curved; capsules immersed, emergent, or variously exserted, erect and symmetric or rarely bulging on 1 side at base, smooth or ribbed when dry; annulus none or well-developed; operculum convex, conic, or rostrate; peristome teeth (generally present) entire, perforate, or irregularly cleft to the middle or less, usually papillose. Calyptrae cucullate or mitrate, sometimes plicate.
The genus is treated here in a sense that includes Coscinodon, Schistidium, and Jaffueliobryum. A s far as the Mexican
species are concerned G. apocarpa and G. rivularis could be referred to Schistidium because of immersed capsules with the
columella falling with the operculum; G. pulvinata is a Coscinodon because of a dioicous inflorescence, narrow, phcate leaves, and capsules lacking an annulus; G. wrightii and G. churchilliana have been placed in Jqffueliobryum, segregated from
Coscinodon, because of autoicous inflorescences, broad, smooth leaves, and annulate capsules.—For further information on
this segregate, see Churchill (1987).
Sterile Grimmias are difficult to name with certainty owing to variability, especially with regard to development of leaf
points, and differences in basal areolation of upper and lower leaves, not always present in poorly developed plants. Geneva
Sayre's key to sterile material (1952) often proves helpful.