Plants in loose tufts, dark green to brownish black. Stems 1--3 cm. Stem leaves ovate lanceolate from an ovate base, 1.7--4 × 0.4--0.8 mm, both margins plane, incurved distally, intermarginal bands absent, awn 0.5--1 mm, not decurrent, acute, costa narrow proximally; distal laminal cells 2-stratose, quadrate, thick-walled; medial laminal cells rounded to quadrate, straight, thick-walled; basal juxtacostal laminal cells usually elongate (sometimes short-rectangular), usually sinuose, and usually with thick lateral walls; basal marginal laminal cells short- to long-rectangular, straight, with thick transverse and thin lateral walls, green, not to distinctly hyaline. Perichaetial leaves enlarged. Seta straight, 4--6 mm. Capsule occasionally present, exserted, yellow-brown, oblong-ovoid, exothecial cells short-rectangular, thin-walled, stomates present, annulus of 2--3 rows, rectangular, thick-walled, operculum long-rostrate, peristome solid, split in distal half. Calyptra cucullate.

Dry, exposed to partially shaded, acidic, sandstone and granite and basalt, montane to alpine; (30--)1000--2450 m; Greenland; Alta, B.C., Ont., Que., Yukon; Ariz., Calif., Colo., Idaho, Minn., Mo., Mont., Nev., N.Mex., Ore., Pa., Tex., Utah, Va., Wash., Wyo.; Eurasia; Africa (Algeria, Morocco).

Grimmia ovalis is common and widespread in high elevation sites in western North America from southern B.C. along the Rocky Mountain corridor to southern New Mexico and south central California. H. A. Crum and L. E. Anderson (1981) rejected all reports and specimens of G. ovalis from eastern North America. However, we have seen specimens from that area, although scattered and rare. It is not surprising that the species occurs in the eastern part of the continent given that it is widespread across the Laurasian continental plates and India. Outlier sites in the Yukon and southern Greenland connect the North American populations to Asia and Europe, respectively. In western North America, Grimmia ovalis is most often confused with G. longirostris and G. laevigata. While superficially similar to G. longirostris, G. ovalis has concave leaves with plane margins and is dioicous, while G. longirostris has keeled leaves with a recurved margin and is autoicous. Other points of separation are discussed under G. longirostris. Typical specimens of G. ovalis are readily separated from G. laevigata by their ovate-lanceolate leaves with a well-defined ovate base and narrowly attached awns. However, both of these species are variable in leaf shape, and while the awn of G. ovalis is usually narrowly attached, sometimes it is quite broad and may boarder on being decurrent. These specimens can be identified by the width of the costa and the basal areolation. Grimmia ovalis has a narrow costa, usually no more than 1/4 to 1/3 of the width of the leaf base, while G. laevigata has a distinctly broad costa covering 1/2 of the base. The basal marginal cells of G. ovalis are short- to long-rectangular and hyaline while those of G. laevigata are oblate to quadrate and not hyaline. In eastern North America, specimens of G. ovalis have been misidentified as G. olneyi. Aside from seta and capsule differences, G. ovalis has rectangular basal marginal laminal cells and its basal juxtacostal cells are long-rectangular to elongate; see also G. olneyi.