1. Costa ending well before the apex; leaf tip rounded to cucullate, muticous; lamina uniformly 1-stratose; laminal cells all quadrate. | G. mollis |
1. Costa reaching apex; leaf tip rounded to acute, muticous or awned; lamina usually with 2-stratose areas towards margins or with 2-stratose ridges; laminal cells oblate, quadrate, rectangular or elongate | → 2 |
2. Seta eccentrically attached to capsule base; capsule immersed, smooth, ventricose; stomata 3-4, large, at base of capsule (subg. Grimmia) | → 3 |
2. Seta centrally attached to capsule base; capsule immersed to exserted, smooth to plicate, not ventricose; stomata none to many, small, at neck to base of capsule | → 6 |
3. Distal leaves concave-keeled; distal lamina 1-stratose or with 2-stratose patches, margins 1- or 2-stratose; annulus absent or reduced to 1-2 rows of small cells; operculum mammillate | → 4 |
3. Distal leaves concave; distal lamina 2-stratose with 2-stratose margins; annulus prominent; operculum rostrate | → 5 |
4. Peristome present, annulus absent; distal lamina 1-stratose, margins 1- or 2- stratose | G. plagiopodia |
4. Peristome absent, annulus present; distal lamina 1-stratose with 2-stratose patches, margins 2-stratose. | G. anodon |
5. Basal laminal cells thick-walled; gonioautoicous; peristome fully developed. | G. americana |
5. Basal laminal cells thin-walled; dioicous; peristome rudimentary. | G. crinitoleucophaea |
6. Leaves merely 1-stratose distally; margins at most narrowly 2-stratose; one or both leaf margins recurved (G. reflexidens plane) (mostly subg. Rhabdogrimmia) | → 7 |
6. Leaves 2-3-stratose distally or 1-stratose with distal margins widely 2-stratose (G. sessitana and some G. donniana); leaf margins incurved, plane or recurved | → 26 |
7. Costa projecting on abaxial side with two wings. | G. ramondii |
7. Costa on abaxial side smooth or angled | → 8 |
8. Leaves muticous, without awns or only distal leaves with very short awn or hyaline tip | → 9 |
8. At least distal or perichaetial leaves with distinct awns | → 13 |
| G. atrata |
| → 10 |
10. Leaves squarrose when moist; medial laminal cells oblate to rounded quadrate | G. lisae |
10. Leaves erect to patent when moist; medial laminal cells quadrate to short-rectangular | → 11 |
11. Basal marginal cells with thickened transverse walls; seta arcuate; globular gemmae occasionally present on leaves. | G. trichophylla |
11. Basal marginal cells with thin transverse walls; seta straight or slightly arcuate; gemmae absent | → 12 |
12. One leaf margin recurved; medial laminal cells sinuose; seta straight or slightly arcuate | G. elongata |
12. Leaf margins both recurved; medial laminal cells with nodulose walls; seta straight. | G. lesherae |
13. Awns nearly equal to or much longer than lamina, decurrent, seta straight to flexuose | → 14 |
13. Awns typically shorter than lamina (G. pulvinata can be long); decurrent or not; seta arcuate to cygneous | → 15 |
14. Awns 1-2 mm, leaf margins plane, [seta straight]; only known from Maritime provinces in North America. | G. reflexidens |
14. Awns 2-4 mm, leaf margins both recurved; seta flexuose; endemic to Montana and Idaho. | G. brittoniae |
15. Leaves abruptly narrowed to awns, apex rounded; autoicous | → 16 |
15. Leaves gradually tapering to awns, apex narrowed; dioicous | → 18 |
16. Operculum rostrate; basal marginal laminal cells quadrate to short-rectangular | G. pulvinata |
16. Operculum mammillate to conical; basal marginal laminal cells short- to long-rectangular | → 17 |
17. Awns only on perichaetial leaves; basal juxtacostal cells with thin, straight walls; marginal distal lamina 2-stratose; acidic rocks. | G. moxleyi |
17. Awns on all distal leaves; basal juxtacostal cells with thick, nodulose walls; marginal distal lamina 1-stratose; basic rocks. | G. orbicularis |
18. Clusters of gemmae easily visible on abaxial side of leaf lamina or on leaf tips | → 19 |
18. Clusters of gemmae absent or in obscure clusters in leaf axils | → 21 |
19. Multicellalar gemmae on abaxial side of leaf lamina in distal leaves; leaves crisped and contored. | G. torquata |
19. Cluster of gemmae only on leaf tips; leaves straight | → 20 |
20. Leaves with blunt eroded apices; distal cells with pseudo- papillose walls; stem central strand present. | G. anomala |
20. Leaves with acuminate apices; distal cells with smooth walls; stem central strand absent. | G. hartmanii |
21. Leaves narrowly ovate-lanceolate to linear-lanceolate, distinctly incurved or contorted when dry. | G. incurva |
21. Leaves lanceolate to ovate-lanceolate, straight, appressed, only occasionally somewhat contorted when dry | → 22 |
22. Central strand absent; basal juxtacostal leaf cells uniformly elongate to linear, strongly nodulose and thick-walled; mid leaf cells extremely sinuose and very thick-walled; leaf margins both recurved | → 23 |
22. Central strand present; basal juxtacostal cells short- to long-rectangular, elongate cells absent or few and scattered; mid leaf cells straight to sinuose, thin- to thick-walled; leaf margins one or both recurved | → 24 |
23. Costa circular, projecting in transverse section; basal marginal cells thin-walled; distal leaves straight, awns not decurrent. | G. attenuata |
23. Costa semicircular, not projecting in transverse section; basal marginal cells thick-walled; distal leaves often secund, awns often decurrent | G. leibergii |
24. Leaves squarrose when moist; mid leaf cells rounded to oblate, straight. | G. lisae |
24. Leaves erect to patent when moist; mid leaf cells rounded-quadrate to short-rectangular, sinuose | → 25 |
25. Blackish green tufts; costa angled or bluntly winged in transverse section; awns denticulate, occasionally decurrent; capsule globose, brown. | G. muehlenbeckii |
25. Yellowish green tufts; costa semicircular in transverse section; awns smooth to slightly denticulate, not decurrent; capsule oblong-ovoid, yellow-green | G. trichophylla |
26. Leaves concave; costa not prominent; margins plane or incurved; dioicous (subg. Litoneuron) | → 27 |
26. Leaves keeled; costa prominent; margins recurved, plane or incurved; autiocous or dioicous (mostly subg. Guembelia) | → 33 |
27. All leaves muticous, straight or falcate | → 28 |
27. At least distal leaves awned, straight | → 29 |
28. Leaves oblong-lanceolate to ligulate, straight, cucullate, obtuse-rounded; basal marginal laminal cells short-rectangular; widely distributed. | G. unicolor |
28. Leaves oblong-lanceolate, homomallous-falcate, subulate, uncinate; basal marginal laminal cells quadrate to short-rectangular; endemic to Pacific Coast region. | G. hamulosa |
29. Leaves oblong-ovate to oblong-lanceolate; basal marginal laminal cells oblate to quadrate; costa broad at base; awn broadly attached and decurrent. | G. laevigata |
29. Leaves ovate-lanceolate from an ovate base; basal marginal laminal cells quadrate to long-rectangular; costa narrow at base; awn typically narrowly attached and not decurrent | → 30 |
30. Costa-like multistratose leaf bands present in transverse section. | G. serrana |
30. Costa-like multistratose leaf bands absent | → 31 |
31. Capsule emergent, gymnostomous, stomata absent, operculum mammilate; basal laminal cells uniformly short-rectangular, straight and thin-walled. | G. nevadensis |
31. Capsule exserted, peristome fully developed, stomata present, operculum rostrate; basal marginal and juxtacostal laminal cells typically contrasting in length or thickness | → 32 |
32. Basal marginal laminal cells quadrate; basal juxtacostal laminal cells quadrate to short-rectangular; seta sigmoid; capsule wrinkled when dry; perichaetial leaves not enlarged; endemic to eastern North America. | G. olneyi |
32. Basal marginal laminal cells quadrate to long-rectangular; basal juxtacostal laminal cells rectangular to elongate; seta straight; capsule smooth when dry; perichaetial leaves enlarged; widely distributed. | G. ovalis |
33. Margins plane or incurved | → 34 |
33. Margins recurved on one or both sides | → 44 |
34. Costa transverse section circular distally; awn hyaline-tipped to short (0.3 mm), decurrent | G. teretinervis |
34. Costa transverse section semicircular distally; awn short to long, usually prominent, decurrent or not | → 35 |
35. Seta arcuate; leaves spirally curved around stem when dry, flagelliform innovations present | G. funalis |
35. Seta straight; leaves straight when dry, flagelliform innovations absent | → 36 |
36. Gemmae abundant on adaxial distal leaf surface. | G. shastae |
36. Gemmae absent on leaves | → 37 |
37. Distal laminal cells bulging | → 38 |
37. Distal laminal cells not bulging | → 40 |
38. Leaf margins plane; cladautoicous; basal juxtacostal laminal cells rectangular to elongate; distal juxtacostal laminal cells 1-stratose; stomata present. | G. sessitana |
38. Leaf margins incurved; dioicous; basal juxtacostal laminal cells quadrate to short-rectangular; distal juxtacostal laminal cells 2-stratose; stomata present or absent | → 39 |
39. Stomata absent; leaves not plicate, not cucullate. | G. alpestris |
39. Stomata present; leaves weakly to rarely strongly plicate distally, cucullate | G. caespiticia |
40. Margins plane throughout; basal marginal laminal cells short- to long-rectangular; stomata present; autoicous | → 41 |
40. Margins incurved distally; basal marginal laminal cells quadrate to short-rectangular; stomata absent; dioicous | → 42 |
41. Distal juxtaxcostal laminal cells 2-stratose, occasionally 1-stratose; basal marginal leaf cells long-rectangular, hyaline; annulus large, of 2 rows of rectangular cells, revoluble; calyptra mitrate. | G. donniana |
41. Distal juxtacostal laminal cells 1-stratose; basal marginal leaf cells short- to long-rectangular, rarely hyaline; annulus small, of 1 row of quadrate cells, not revoluble; calyptra cucullate. | G. sessitana |
42. Capsule immersed to emergent, wide-mouthed, peristome rudimentary; endemic to California. | G. mariniana |
42. Capsule exserted, narrow-mouthed, peristome present, fully developed; widespread in western North America | → 43 |
43. Basal juxtacostal laminal cells short- to long-rectangular, distinct from quadrate to short-rectangular basal marginal cells; medial laminal cells rounded, thick-walled. | G. montana |
43. Basal juxtacostal and marginal cells quadrate to short-rectangular, basal areolation relatively uniform; medial laminal cells quadrate to short-rectangular, thin-walled. | G. alpestris |
44. Leaves muticous, cucullate. | G. atrata |
44. Leaves awned, not cucullate | → 45 |
45. Leaves spirally curved around stem when dry, flagelliform innovations present. | G. funalis |
45. Leaves straight when dry, flagelliform innovations absent | → 46 |
| → 47 |
| → 51 |
| → 48 |
| → 49 |
48. Stem central strand present, epidermis thin; leaf margins 2-stratose, not thickened, one margin recurved (rarely both); leaves broadly ovate- lanceolate. | G. arizonae |
48. Stem central strand absent, epidermis thick; leaf margins 3(-4) stratose, thicker than juxtacostal lamina, usually both margins recurved; leaves narrowly lanceolate from an ovate base. | G. pilifera |
49. Seta arcuate; dioicous. | G. elatior |
49. Seta straight; autoicous | → 50 |
50. Annulus small, 1 row of quadrate cells; stomata in 1 row; basal juxtacostal cells straight and thin-walled. | G. sessitana |
50. Annulus prominent, 2 rows of rectangular cells; stomata in 2-3 rows; basal juxtacostal cells sinuose and thick walled. | G. longirostris |
51. Basal juxtacostal cells straight, thin-walled; distal juxtacostal lamina 1-stratose, cells often bulging; plants small (less than 1 cm), blackish; moist, alpine habitats. | G. sessitana |
51. Basal juxtacostal cells sinuose, thick-walled; distal juxtacostal lamina at least 2-stratose, cells not bulging; plants robust (greater than 1cm), yellow-green to very dark olivaceous; dry, widely distributed | → 52 |
52. Leaf margins 2-stratose, not thickened; stem central strand present, epidermis thin | → 53 |
52. Leaf margins multistratose and thickened; stem central strand absent, epidermis thick | → 54 |
53. Autoicous; costa transverse section reniform; leaves sheathing; widely distributed. | G. longirostris |
53. Dioicous; costa transverse section semicircular; leaves not sheathing; American Southwest | G. arizonae |
54. Leaves narrowly lanceolate from an ovate base, usually narrowly recurved on both margins; distal lamina without multistratose bands, never papillose. | G. pilifera |
54. Leaves broadly lanceolate, broadly recurved on one margin; distal lamina with multistratose bands, occasionally papillose | G. elatior |