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.)

As reported by R. R. Ireland (1982b), Grimmia teretinervis is widely scattered across North America, but nowhere is it common. R. I. Hastings (2002) added several more Western collection locations to those reported by Ireland. Based on field observations and by correlating collecting localities with bedrock geology, Hastings proposed that the distribution of G. teretinervis in North America is largely correlated with the boundaries of ancient epicontinental seaways. These deposits have subsequently undergone faulting or were subjected to glacial-fluvial erosion. The ancient oceans provided the calcareous sediments, and the faulting and erosion created the steep exposures preferred by G. teretinervis. Sporophytes have never been observed for this species and, until reported by Ireland, antheridial plants also were unknown. Despite the lack of sporophytes, this species is readily identified by its unique costal structure, which is circular in transverse section. It commonly has thick-walled, bulging laminal cells and very short awns that are none-the-less often long-decurrent. These features give the plants a blackish brown, shiny thread-like appearance.

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