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 anodon is widespread and common across the western United States and the mountains of southern Alberta and British Columbia. It is absent from eastern North America except around the Great Lakes and individual sites in the Gaspé Peninsula and New Brunswick. It extends sparsely into the Yukon and Alaska. These high latitude sites are strongly correlated with glacial refugia or areas of early deglaciation. Most eastern United States collecting localities are near the margin of the Wisconsinan continental ice sheet. The west-east disjunction of the species suggests the disruption of a more continuous distribution by Wisconsinan glacial events. It is widespread elsewhere in the northern hemisphere on calcareous outcrops and disturbed sites. Usually fertile, G. anodon is recognized easily by its immersed, gymnostomous capsule, on a sigmoid seta. The other widespread species in the subgenus, G. plagiopodia, has peristome teeth. When sterile these species can be difficult to differentiate, but G. anodon has leaves that are more keeled with 2-stratose margins, while leaves of G. plagiopodia tend to be more concave and are more uniformly 1-stratose. Grimmia anodon is rather similar to Schistidium flaccidum. However, the latter is characterized by a short, straight seta, leaves sharply keeled distally, and leaf margins plane at base but recurved distally on both sides.

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