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 leibergii, formerly thought to be endemic to western North America, has the habit of Racomitrium heterostichum. Nearly all specimens of G. leibergii in NY, and probably also in other North American herbaria, have been filed as varieties of R. heterostichum (= Bucklandiella heterosticha). This confusion probably accounts for G. leibergii not being commonly recognized in North America. J. B. Leiberg (1893) stated that it is most closely related to G. decipiens, a species that does not occur in North America. Both taxa share broadly ovate-lanceolate leaves with both margins recurved, rectangular mid leaf cells with extremely thick and sinuose lateral walls and elongate to linear, nodulose, thick-walled basal juxtacostal cells. However, G. decipiens is autoicous, it is a much smaller species, with long, sharply denticulate awns. The gametophytes form comal tufts, so the distal leaves are 2–3 times longer than the lower leaves, and are not secund. Grimmia jacutica has been described separately from eastern Asia and Alaska but all specimens of it that we have examined are just slightly smaller forms of G. leibergii with slightly more sinouse mid leaf cells. The extension of G. leibergii into eastern Asia is a significant find and speaks to our poor knowledge of Grimmia distribution patterns on a worldwide basis.

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