Flora of North America species comparison

In North America, Grimmia trichophylla is principally a lowland species, occurring in the mountains up to about 1000 m., rarely higher. In the Southern Hemisphere, it may be found up to 4000 m. In New Zealand, the species is common, and in contrast to G. trichophylla in North America, frequently bears capsules. The New Zealand plants are usually smaller than American specimens, and the leaves are frequently contorted. The nearly cosmopolitan G. trichophylla has many phenotypes, and numerous subspecies and varieties have been described. In damp and shaded habitats, the awns may be short, just as in dry unfavorable habitats at high altitudes, where stunted specimens may occur with small, short leaves and reduced awns, or even with muticous leaves. Grimmia trichophylla has frequently been confused with related species such as 36. G. muehlenbeckii and 34. G. lisae (see discussions thereunder for identification details). Robust forms of G. trichophylla have been mistaken for G. austrofunalis (H. C. Greven 1997, 2003), which does not occur in North America. Although some of those plants have leaves of equal length along the stem, characteristic of G. austrofunalis, they also have both leaf margins recurved, and the medial and outer basal laminal cells are longer and more robust than in that species.

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

Grimmia elongata is a widely distributed species mainly occurring above 2000 m, and with a preference for acidic sandstones and volcanic, damp, north-facing outcrops and ledges. It seems to be uncommon in North America, having been collected only occasionally and from widely separated localities. However, the wide distribution of G. elongata across the Northern Hemisphere suggests that it may be more common on this continent than collection records indicate. Cao T. and D. H. Vitt (1986b) noted that in North America, specimens of G. elongata would be confused most likely with G. donniana, as they considered the two species to be closely related. However, these species are distinctly different in a number of clear characters: G. elongata is reddish brown, muticous or short-awned, has one leaf margin recurved and is dioicous. In contrast, G. donniana is green to black, long-awned, has plane leaf margins and is autoicous. These characters lead us to believe that these species are not closely related; H. C. Greven (2003) believed that G. elongata is most closely related to the Himalayan endemic G. redunca Mitten.

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