Flora of North America species comparison

Grimmia ovalis is common and widespread in high elevation sites in western North America from southern British Columbia along the Rocky Mountain corridor to southern New Mexico and south central California. H. A. Crum and L. E. Anderson (1981) rejected all reports 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 in India. Outlier sites in the Yukon and southern Greenland connect the North American populations to those in Asia and Europe, respectively. In western North America, G. 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 border on being decurrent. These specimens can be identified by the width of the costa and the basal areolation. Grimmia ovalis has a costa that is narrow at the base, while G. laevigata has a distinctly broad costa covering up to 1/3 of the base. The basal marginal cells of G. ovalis are most often short- to long-rectangular and hyaline while those of G. laevigata are always 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 under G. olneyi.

Based on identifications by Greven, W. A. Weber et al. (2003) reported Grimmia bernoullii in the United States. That species differs from G. ovalis by its more ovate leaves without shoulders and with plane margins, costa broad at the base and disappearing in mid leaf, and sporophytically by its ellipsoid capsule with long-rostrate, straight operculum, and mitrate calyptra. Hastings has examined duplicate specimens from Missouri of those cited by Weber et al. and has determined that they do not deviate significantly from G. ovalis, having rather narrow leaves, costa narrow at the base and remaining strong in mid leaf, and with many leaves having incurved margins. The specimens were sterile and therefore sporophytic characters could not be determined. Based on these observations Hastings excludes G. bernoullii from the North American flora, although Greven would still retain the species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

In North America, Grimmia crinitoleucophaea is known from only scattered localities in the American west and in three extremely disjunct sites in Canada: in southern British Columbia, near the Keele River of the Northwest Territories, and along the Dempster Highway in the Yukon. It is found on a broad range of both basic and acidic rock types. Its subgeneric placement is problematic. Gametophytically the species is inseparable from G. tergestina, of subg. Litoneuron. Indeed, based on areolation and leaf shape, L. Loeske (1913–1914, part 1) placed it as a subspecies of the latter. This close similarity may account for reports by J. Muñoz and F. Pando (2000) and D. H. Norris and J. R. Shevock (2004) of G. tergestina from North America. We have seen all cited specimens in these papers and they all represent G. crinitoleucophaea or G. ovalis. Therefore, we reject G. tergestina being in North America. Sporophytic characters of G. crinitoleucophaea (a short, arcuate to sigmoid seta that is eccentrically attached to the capsule, an immersed ventricose capsule with a small, mitrate calyptra, and 3–4 large stomata) clearly indicate membership in subg. Grimmia. Further, G. crinitoleucophaea and G. tergestina have never been collected together, suggesting that the two are also ecologically distinct. Despite its dioicous sexuality, G. crinitoleucophaea is usually fertile; its rudimentary peristome and large annulus are thus readily evident. Its 2-stratose laminal stratification separates it from specimens of G. plagiopodia that may have broken peristome teeth.

(Discussion copyrighted by Flora of North America; reprinted with permission.)