Flora of North America species comparison

Of conservation concern.

Previous to its discovery in Iceland, as Grimmia grisea (H. C. Greven 1998), G. reflexidens was known from only the Southern Hemisphere. It had previously been collected east of East Bay, Newfoundland, now the only known locality in North America, but was not recognized as G. reflexidens. The latter is similar to G. asperitricha Dixon & Sainsbury of New Zealand, and the two species have been confused by G. O. K. Sainsbury (1945) as well as by R. Ochyra (1993). J. Muñoz (1998b) synonymized G. reflexidens with G. sessitana. However, the former is readily separated from the latter by: (1) enlarged perichaetial leaves, (2) decurrent awns, (3) non-bulging laminal cells, and (4) dioicous sexual condition. Capsules are unknown from Northern Hemisphere material, but G. reflexidens lacks stomata while they are present for G. sessitana. Although G. reflexidens and G. teretinervis both have decurrent awns they are easily separated by a number of characters: G. reflexidens grows in compact cushions, has long awns, and a semicircular costa; G. teretinervis grows in loose clumps, is hyaline-tipped to short-awned, and has a unique costa that is distally almost completely circular in transverse section.

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

Grimmia elatior is fairly common in the Canadian Rockies and in the western United States. It is predominantly bound to the Rocky Mountain area in Colorado, Wyoming, and Montana. In eastern North America it is known only from a site in New Jersey. It can be recognized easily by its robust habit, usually growing in dark green, extended patches on various types of acidic rock, like gneiss, granite, and sandstone. While it is often described as having papillae, most North American specimens do not have them. E. M. Mair (2002) reported that papillae were strongly expressed in harsh conditions but many specimens from the alpine in both the Yukon and Colorado lack papillae. The widespread but uncommon western species G. leibergii is commonly mistaken for G. elatior. However, the former has both leaf margins recurved, its lamina is 1-stratose with only 2-stratose margins, and its basal juxtacostal cells are elongate to linear; in G. elatior there is only one recurved leaf margin, its lamina is 2-stratose with multistratose bands and margins, and its basal juxtacostal cells are only short- to long-rectangular. The length of the awn in G. elatior is quite variable; plants with nearly muticous leaves and plants with very long awns may be found growing close together. There is also some resemblance to G. pilifera, widespread in Asia and eastern North America. The latter, however, has immersed capsules, both margins are recurved, and its lamina does not have multistratose bands.

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