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.)

Of conservation concern.

Grimmia atrata is rare in North America, being known only from three widely scattered areas. It is known to geologists as one of the “copper-mosses,” i.e., it is an indicator of heavy-metal-bearing rock. Because it prefers damp gneiss and mica schists, the tufts are often orange inside on account of the presence of heavy-metal oxides. The placement of G. atrata has been problematic. Because of the curved distal leaves and the absence of awns, it does not immediately appear to be a Grimmia. As a result it has previously been placed in a separate genus, Dryptodon, intermediate between Grimmia and Racomitrium. Following Cao T. and D. H. Vitt (1986b), Hastings placed it in subg. Guembelia based on its thick, keeled leaves, long, straight setae, and smooth capsules. With its recurved margin, rectangular, thick-walled, sometimes sinuous basal laminal cells, prominent annulus, and mitrate calyptra, it would seem closest to the group including G. longirostris and G. pilifera. However, its large size and muticous, cucullate leaves, which are often ligulate, coupled with its preference for moist habitats, readily separate this species from other members of this group. Sterile specimens with 1-stratose laminae may be confused as belonging to the subg. Rhabdogrimmia. In densely shaded habitats, it grows in loose patches and the areolation shows a near absence of sinuosity. On dry rock, however, the plants have extremely thick, nodulose cell walls that place the species firmly in Grimmia.

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