Authors: Roxanne I. Hastings & Dr. Henk C. Greven

Plants in compact hairy cushions, greyish-green. Stems 1--2 cm, central strand absent. Stem leaves ovate to oblong-lanceolate, 0.1--1.15 × 0.3--0.5 mm, keeled, not plicate, margin plane, awns 1--2 mm, very long, smooth to slightly denticulate, flattened basally, long-decurrent, costal transverse section prominent, terete; distal laminal cells yellowish-green, 1-stratose with 2-stratose ridges, not bulging, marginal cells 2-stratose, not bulging; medial laminal cells rounded quadrate, slightly sinuose, thick-walled; basal juxtacostal laminal cells rectangular, sometimes nodulose, thin to thick-walled; basal marginal laminal cells rectangular with thickened transverse walls, pellucid in 2--4 rows. Perichaetial leaves enlarged. Sexual condition dioicous. [Seta straight, 1.5--2 mm. Capsule absent in northern hemisphere material, emergent to shortly exserted, yellowish-brown, obloid, exothecial cells irregularly short-rectangular, thin-walled, stomates absent, annulus of 1 row, quadrate, thick-walled, operculum mammillate to rostrate, peristome present, nearly fully developed, split and perforated only in apex, papillose.]

Dry acidic rock; 50[--300] m; of conservation concern; Nfld.; South America (Argentina, Chile); Europe (Iceland); Australia; Pacific Islands (New Zealand).

Previous to its discovery in Iceland (H. C. Greven 1998), Grimmea grisea was known from only the Southern Hemisphere. It had previously been collected in Newfoundland, but was not recognized as being this species. It is known in North America from a single locality east of East Bay, Newfoundland. Grimmia grisea is close to Grimmia asperitricha of New Zealand and both species have been confused by G. O. K. Sainsbury (1945) as well as by R. Ochyra (1993). J. Muñoz (1998b) synonymized G. grisea with G. reflexidens. However, E. Maier (2002) made it clear that the type specimen of G. reflexidens is a Coscinodon, thus that synonomy is in error. Grimmia grisea is readily separated from G. sessitana 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. grisea lacks stomates while they are present for G. sessitana. Although G. grisea and G. teretinervis both have decurrent awns they are easily separated by a number of characters: G. grisea grows in compact cushions, has long awns, and a terete costa; G. teretinervis grows in loose clumps, is hyaline-tipped to short-awned and has a unique costa that is completely circular in transverse section distally.