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 plagiopodia has a widespread and continuous distribution on calcareous rock across the northern Great Plains, reaching as far east as Illinois. It is rare in eastern North America, with a disjunct site in southern Ontario. In the west it reaches into the mountains on limestone and basic sandstone deposits, but its continuous range does not extend west of a line from Utah to south-central British Columbia. There is a disjunct location near Carson City, Nevada and Lake Tahoe, California. In the Arctic it is known from a few scattered localities extending from northwestern Greenland and nearby Ellesmere Island to the North Slope of Alaska. Compared to G. anodon, G. plagiopodia tends to occupy more prairie-like sites and is typically found at lower elevations. Commonly fertile, it is recognized by its immersed, peristomate capsule on a sigmoid seta with fully-developed teeth that are perforated and split distally. Grimmia americana is similar but has a short, straight to arcuate seta and a large annulus. The other widespread species in the group, G. anodon, has an annulus and is gymnostomous.

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