1. Leaves usually lanceolate; margins plane to involute; costa shortly excurrent, usually with 2 stereid bands 2
1. Leaves lanceolate to ligulate or spathulate; margins plane to recurved; costa ending below the apex or long excurrent, with dorsal stereid band or 2 stereid bands........................................................................................ 7
2. Upper lamina bistratose medially, the cells not vertically aligned near the costa but grading to vertically evenly stacked toward the leaf margins
..................................................................................... 30. Timmiella
2. Upper lamina nearly always unistratose, if bistratose (rarely) then the upper cells vertically situated directly over the lower cells throughout........................................................................................................ 3
3. Leaves long linear-lanceolate, strongly sheathing at the base; margins plane; ventral stereid band larger than the dorsal band
............................................................................................................... 24. Pseudosymblepharis
3. Leaves lanceolate to oblong-lanceolate or oblong-ovate, not sheathing at the base; margins plane, erect, or weakly to strongly incurved or recurved; ventral stereid band smaller than the dorsal or absent.................... 4
4. Leaf margins distinctly involute even when moist
....................................................................... 36. Weissia
4. Leaf margins plane or erect, or somewhat incurved near the apex when dry............................................... 5
5. Basal leaf cells, if differentiated, not forming a V-shaped region across the base; peristome teeth short, erect, often bifid
........................................................................................................................ 33. Trichostomum
5. Basal leaf cells forming a V-shaped region with hyaline cells extending upward along the leaf margins; peristome teeth long, twisted................................................................................................................................ 6
6. Leaf margins coarsely dentate, upper marginal cells rectangular and clearly longer than median cells; perichaetia lateral on main axis or at ends of short lateral branches
................................ 22. Pleurochaete
6. Leaf margins entire, upper marginal cells not longer than median cells; perichaetia terminal on main axis...............................................................................................................................................................................
.......................................................................................................................................................... 31. Tortella
7. Leaves bearing lamellae or filaments on the upper dorsal surface of the costa................................................ 8
7. Leaves without lamellae or filaments on the costa............................................................................................ 10
8. Stem central strand absent; leaves fleshy; margins inflexed; costa percurrent or shortly excurrent, ending in a reddish awn
....................................................................................................................... 1. Aloina
8. Stem central strand present; leaves thin; margins plane or recurved; costa long-excurrent as a hyaline awn.......................................................................................................................................................................... 9
9. Leaf margins revolute; costa bearing branched filaments
............................................................. 7. Crossidium
9. Leaf margins plane; costa bearing 2–3 longitudinally inserted lamellae
........................... 25. Pterygoneurum
10. Leaves usually lingulate to spathulate or broadly ovate-lanceolate; costa with dorsal stereid band only; upper leaf cells mostly larger, lax............................................................................................................... 11
10. Leaves usually lanceolate to lingulate; costa with two stereid bands; upper leaf cells mostly small.... 22
11. Leaves mostly spathulate or narrowly lingulate; basal leaf cells mostly short-rectangular; upper leaf cells ventrally mammillose-bulging, dorsally weakly convex................................................................................. 12
11. Leaves often broadly ovate-lanceolate or narrowly spathulate; basal leaf cells usually broadly long-rectangular; upper leaf cells convex on both surfaces, smooth or papillose................................................. 14
12. Peristome absent; leaf cells smooth, or only somewhat bulging
.................................... 27. Scopelophila
12. Peristome present; mammillose-bulging.................................................................................................. 13
13. Costa dorsal epidermis present; leaves linear-lingulate, with the V-shaped area of inflated hyaline cells at the base; peristome teeth 16, widely spaced
............................................................................... 35. Weisiopsis
13. Costa dorsal epidermis absent; leaves narrowly spathulate, without the distinct V-shaped area at the base; peristome teeth 32, closely set
.................................................................................................... 19. Luisierella
14. Plants minute, usually 1.5–3.0(–5.0) mm tall; peristome absent or rudimentary................................. 15
14. Plants usually more than 5.0 mm tall; peristome present, filaments...................................................... 18
15. Leaves acute to acuminate, mostly piliferous; capsules immersed, spherical, inoperculate
..... 21. Phascum
15. Leaves apiculate to short-awned, or rounded at the apex; capsules long-exserted, cylindrical, setae elongated, operculate......................................................................................................................................... 16
16. Leaf apices rounded or rounded obtuse; costa ending just above the leaf-middle.............
11. Gymnostomiella
16. Leaf apices apiculate to short-awned; costa excurrent............................................................................ 17
17. Plants bud-like, silver-green; upper leaf cells rhombic, smooth; peristome rudimentary
......... 28. Stegonia
17. Plants not bud-like, green; upper leaf cells quadrate or hexagonal, pluripapillose, rarely smooth; peristome absent
.................................................................................................................................... 23. Pottia
18. Leaf cells smooth, basal cells weakly differentiated from the median-cells........................................ 19
18. Leaf cells papillose, basal cells distinctly differentiated from the median-cells................................. 20
19. Leaf margins plane or only weakly recurved near the base; costa percurrent
................................... 6. Chenia
19. Leaf margins strongly revolute; costa excurrent, ending in a hyaline awn
.................................. 14. Hilpertia
20. Leaves not crisped or not distinctly contorted when dry; leaf cells laxer, pellucid; peristome teeth nearly erect and free
............................................................................................................. 8. Desmatodon
20. Leaves usually contorted when dry; leaf cells firm, less pellucid; peristome teeth wound in spiral... 21
21. Plants usually larger, to 12 cm tall; leaf cells broader; costa often long-excurrent, ending in a long-hyaline awn, costa dorsal epidermis absent; peristome with a high basal membrane
............... 29. Syntrichia
21. Plants usually smaller, to 2 cm high; leaf cells narrower; costa shortly excurrent, rarely with a hyaline awn, costa dorsal epidermis present; peristome with a low basal membrane
................................ 32. Tortula
22. Leaf margins plane to only weakly recurved; peristome absent, reduced or rudimentary; perichaetia terminal or lateral........................................................................................................................................ 23
22. Leaf margins recurved (rarely plane); peristome teeth usually well developed, sometimes reduced; perichaetia usually terminal....................................................................................................................... 30
23. Plants densely covered with rhizoids; leaves usually linear-lanceolate; capsules lateral............................ 24
23. Plants with rhizoids at the base; leaves lanceolate; capsules terminal........................................................... 25
24. Costa ventral epidermis absent; leaves strongly keeled, base not clearly differentiated
....................... 2. Anoectangium
24. Costa ventral epidermis present; leaves plane, base clearly differentiated
........................ 20. Molendoa
25. Peristome reduced or rudimentary................................................................................................................... 26
25. Peristome absent................................................................................................................................................ 28
26. Plants only to 4 mm tall; leaf apices blunt; costa ending below the apex, with ventral stereid band weakly developed; annuli highly vesiculous
....................................................................... 13. Gyroweisia
26. Plants larger than 5 mm, to 25 mm tall; leaf apices acuminate; costa percurrent to shortly excurrent, with ventral stereid band well developed; annuli not or weakly vesiculous........................................... 27
27. Stem central strand absent; leaf margins serrulate above the shoulder; leaves channeled
...... 10. Eucladium
27. Stem central strand present; leaf margins entire; leaves not channeled
............................... 34. Tuerckheimia
28. Leaves three-ranked, sheathing at the base; leaf cells smooth, basal marginal cells differentiated; costa dorsal epidermis present
............................................................................................... 26. Reimersia
28. Leaves multi-ranked, not sheathing at the base; leaf cells papillose, basal marginal cells not differentiated; costa dorsal epidermis absent........................................................................................... 29
29. Costa ending 2–5 cells below the apex, costal ventral epidermis present; stem central strand present.........
.................................................................................................................................................. 12. Gymnostomum
29. Costa usually excurrent as a mucro, costal ventral epidermis absent; stem central strand absent...................
................................................................................................................................................. 16. Hymenostylium
30. Stem central strand absent; leaves coarsely dentate above, high-sheathing at the base; upper leaf cells strongly thick-walled; perichaetial leaves usually strongly differentiated, convolute-sheathing.............
............................................................................................................................................ 18. Leptodontium
30. Stem central strand present; leaf margins entire or crenulate, leaves low-sheathing or scarcely differentiated at the base; perichaetial leaves somewhat differentiated or only half-sheathing.......... 31
31. Leaves ligulate to spathulate; margins plane or broadly incurved; leaf cells mammillose-bulging or smooth; peristome absent
................................................................................................................ 17. Hyophila
31. Leaves mostly lanceolate or lanceo-lingulate; margins usually recurved; leaf cells with bifid papillae, rarely simple; peristome present, rarely absent............................................................................................... 32
32. Perichaetial leaves with a high-sheathing base; setae 4–6 mm long; peristome absent................
4. Bellibarbula
32. Perichaetial leaves without a high-sheathing base; setae 5–20 mm long; peristome present.............. 33
33. Leaves lanceo-lingulate; leaf cells pellucid, less densely papillose or nearly smooth; cells of adaxial surface of costa mostly rounded quadrate or rarely short-rectangular, papillose or smooth, thin-walled; inner perichaetial leaves small
................................................................................................ 15. Hydrogonium
33. Leaves narrowly ovate-lanceolate; leaf cells not pellucid, densely papillose; cells of adaxial surface of costa mostly rectangular to narrowly rectangular; inner perichaetial leaves large....................................... 34
34. Leaf basal cells well differentiated, lax and thin-walled; margins often irregularly serrate near the apex; leaves becoming reddish when old
............................................................... 5. Bryoerythrophyllum
34. Leaf basal cells not particularly differentiated, firm- to thick-walled; margins usually entire; leaves not becoming reddish when old................................................................................................................. 35
35. Upper leaf cells short-rectangular to rounded rectangular, usually densely papillose, cells less pellucid; costa dorsal and ventral stereid bands well developed; axillary hairs 4–10 cells long; peristome teeth 32, mostly wound together and twisted
..................................................................................................... 3. Barbula
35. Upper leaf cells rounded quadrate or rhombic, smooth or bluntly papillose, cells pellucid; costa ventral stereid band weakly developed; axillary hairs 3–4 cells long; peristome teeth 16 or 32, erect, obliquely or weakly spiraled
.............................................................................................................................. 9. Didymodon