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 anodon is widespread and common across the western United States and the mountains of southern Alberta and British Columbia. It is absent from eastern North America except around the Great Lakes and individual sites in the Gaspé Peninsula and New Brunswick. It extends sparsely into the Yukon and Alaska. These high latitude sites are strongly correlated with glacial refugia or areas of early deglaciation. Most eastern United States collecting localities are near the margin of the Wisconsinan continental ice sheet. The west-east disjunction of the species suggests the disruption of a more continuous distribution by Wisconsinan glacial events. It is widespread elsewhere in the northern hemisphere on calcareous outcrops and disturbed sites. Usually fertile, G. anodon is recognized easily by its immersed, gymnostomous capsule, on a sigmoid seta. The other widespread species in the subgenus, G. plagiopodia, has peristome teeth. When sterile these species can be difficult to differentiate, but G. anodon has leaves that are more keeled with 2-stratose margins, while leaves of G. plagiopodia tend to be more concave and are more uniformly 1-stratose. Grimmia anodon is rather similar to Schistidium flaccidum. However, the latter is characterized by a short, straight seta, leaves sharply keeled distally, and leaf margins plane at base but recurved distally on both sides.

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