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 elatior is fairly common in the Canadian Rockies and in the western United States. It is predominantly bound to the Rocky Mountain area in Colorado, Wyoming, and Montana. In eastern North America it is known only from a site in New Jersey. It can be recognized easily by its robust habit, usually growing in dark green, extended patches on various types of acidic rock, like gneiss, granite, and sandstone. While it is often described as having papillae, most North American specimens do not have them. E. M. Mair (2002) reported that papillae were strongly expressed in harsh conditions but many specimens from the alpine in both the Yukon and Colorado lack papillae. The widespread but uncommon western species G. leibergii is commonly mistaken for G. elatior. However, the former has both leaf margins recurved, its lamina is 1-stratose with only 2-stratose margins, and its basal juxtacostal cells are elongate to linear; in G. elatior there is only one recurved leaf margin, its lamina is 2-stratose with multistratose bands and margins, and its basal juxtacostal cells are only short- to long-rectangular. The length of the awn in G. elatior is quite variable; plants with nearly muticous leaves and plants with very long awns may be found growing close together. There is also some resemblance to G. pilifera, widespread in Asia and eastern North America. The latter, however, has immersed capsules, both margins are recurved, and its lamina does not have multistratose bands.

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