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.)

Of conservation concern.

Grimmia brittoniae is an endemic of western Montana and northern Idaho. It was described by Williams based on a set of specimens that he collected near Columbia Falls. It grows in warm, dry but climatically moist valley-bottom or piedmont forests dominated by Douglas fir. It is distinctive and easily recognized in the field. The often extensive cushions found on rocky underhangs are a characteristic blue-green color when moist, cracking into polygonal patterns when dry. The extremely long awns at once separate it from all other species of the genus. Grimmia brittoniae can be confused only with small forms of G. funalis, which also may grow in compact hoary cushions that are glaucous green in the distal part and brown inside. J. Muñoz (2000) synonymized G. brittoniae with that species. H. C. Greven and T. Spribille (1999), however, had already demonstrated that in G. funalis the leaves are usually spirally curved, the distal areolation is 2-stratose, the proximal leaves are blackish with short awns, the margins are plane or recurved on one side, and the basal cells are linear, thick-walled, and sinuose. In addition, G. funalis is characterized by male plants growing in separate cushions, with muticous to very short-awned leaves. Male plants of G. brittoniae grow intermingled with female ones and can hardly be separated from them. Grimmia brittoniae is more closely related to G. orbicularis. The leaves of both species are similar. However, the awns of the latter are much shorter, it is autoicous, usually with capsules on arcuate setae, the peristome teeth are broad, cribrose, and irregularly cleft at the apex, and the operculum is mammillate. Although Williams originally described G. brittoniae as having concave leaves with plane, sometimes 2-stratose margins, the leaves are keeled distally, and the margins are narrowly recurved and only very rarely 2-stratose. The recurved margins, however, are only present in leaves still attached to the stems; once detached and pressed under a cover glass, the margins appear plane.

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