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 laevigata is widespread and relatively common on the southern Great Plains, into the Ozarks, and along the Appalachians from northeastern Alabama to New England. There is also an extensive outlier in southern Minnesota and adjacent states. In western North America, it is abundant in California and the Pacific Northwest region into south central British Columbia. Although it occurs in the Rocky Mountain region it is not common there, being found mostly in lower elevation sites and along the east slopes. With the exception of a few disjunct sites in southern Georgia and Florida, it is unknown from the coastal plains of the American southeast. This is probably related to the extensive cover of calcareous Cretaceous and more recent bedrock. The northern limit of G. laevigata suggests a distribution influenced by the winter position of the Arctic airmass. Although known from high elevations, it is most often found below treeline on granite and acidic sandstones. It is an early successional invader of granitic rocks in the southeastern piedmont (H. J. Oosting and L. E. Anderson 1937, 1939; C. Keever et al. 1951). Classic specimens of G. laevigata are recognized by their broad leaves with almost no shoulder separating the proximal and distal lamina, and by their robust, broadly attached and long-decurrent awns. However, G. laevigata is quite variable with respect to leaf shape and awn attachment, with some specimens having bases approaching ovate and then often with rather narrowly attached awns. These specimens may be assigned to G. laevigata by the wide costa and oblate to quadrate basal marginal cells. Sterile specimens may be separated from G. crinitoleucophaea by the wide costa and thick-walled basal cells.

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