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.)

In Canada, Grimmia unicolor is found predominantly around the Great Lakes of southern Ontario eastward into southwestern Quebec, with a disjunct site in Newfoundland. In the United States, it is also commonly found in the Great Lakes region and extending eastward into southwestern Maine. The disjunct sites in British Columbia and on the Seward Peninsula may be a Beringial link with populations in Asia, where this species is widely distributed, and in northern Europe. Grimmia unicolor is often found in the splash zone of rocky shorelines, especially cliffs, and along rivers. This habitat is rarely occupied by other species of the genus, except for G. olneyi. Grimmia unicolor is readily distinguished from other species in the subgenus by its leaf morphology. Its leaves are oblong-lanceolate to ligulate, with an obtuse, rounded apex which is muticous. Grimmia olneyi has an acute leaf apex with long awns, and its basal marginal cells are quadrate, contrasting with the rectangular cells of G. unicolor. Sporophytically, G. unicolor typically has a straight seta while that of G. olneyi is sigmoid. Grimmia unicolor has a much narrower costa proximally and lacks an awn, in marked contrast to the broad costa and robust awn of G. laevigata. The leaf shapes of these two species are distinct, with G. unicolor having a pronounced ovate base and narrow leaves tending towards being ligulate, while G. laevigata has broadly oblong-ovate leaves without a shoulder separating the distal and proximal lamina.

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