1. Plants whitish to silvery green (leaves hyaline above)............................................................2
1. Plants green, yellowish green or reddish, not whitish to silvery (leaves not hyaline)..........................5
2. Plants pure whitish, glossy, tomentose; leaf apex slenderly long-acuminate to long-aristate.............. 19. B. gossypinum
2. Plants whitish, pale green, green; leaf apex shortly acuminate, acute or obtuse.................................3
3. Capsules erect...............................................................................32. B. petelotii
3. Capsules cernuous to pendulous......................................................................................4
4. Leaf cells rhomboidal; capsules pyriform, more than 1.5 mm long...................................... 5. B. argenteum
4. Leaf cells sublinear to linear; capsules subglobose, less than 1.0 mm long.............. 24. B. leucophylloides
5. Rhizoids with gemmae......................................................................................................6
5. Rhizoids without gemmae................................................................................................9
6. Gemmae disk-like, flat..................................................................................41. B. tuberosum
6. Gemmae pyriform or globose..............................................................................................7
7. Gemmae pyriform, less than 100 µm long, ca. 2–3 row-cells wide.......................39. B. sauteri
7. Gemmae globose, longer than 150 μm, more than 3 row-cells wide................................8
8. Cell surface of gemmae convex................................................................9. B. bornholmense
8. Cell surface of gemmae smooth..............................................................35. B. radiculosum
9. Plants autoicous.....................................................................................10
9. Plants dioicous.........................................................................................12
10. Endostome and cilia well developed; spores less than 20 μm in diameter........................ 30. B. pallescens
10. Endostome and cilia reduced; spores 25–40 μm in diameter....................................11
11. Leaves ovate to broadly ovate; margins bordered by 1 row of cells; capsules rounded-ovoid to long-ellipsoidal, mouth symmetrical..................................................................11. B. calophyllum
11. Leaves ovate-lanceolate; margins bordered by 2 rows of cells; capsules elongate-ovoid to pyriform, mouth oblique, asymmetrical..............................................................................43. B. uliginosum
12. Leaf apices obtuse and apiculate..........................................................................13
12. Leaf apices acute or acuminate..............................................................................16
13. Leaves almost plane; margins bordered by 1–2 rows of cells or barely differentiated.................14
13. Leaves concave; margins bordered by more than 2 rows of cells.......................................15
14. Leaf apices obtuse; costae ending below the apex........................................16. B. cyclophyllum
14. Leaf apex apiculate; costae percurrent...............................................................18. B. funkii
15. Leaf cells narrowly rhombic; leaf apices round to obtuse, often split; margins bluntly dentate............ 20. B. handelii
15. Leaf cells broadly rhombic; leaf apices obtuse to apiculate; margins entire to serrulate .............27. B. neodamense
16. Marginal cells of leaves not or hardly differentiated................................................................17
16. Marginal cells of leaves clearly differentiated.......................................................................30
17. Apophyses short and thick.................................................................................................18
17. Apophyses long and slender.............................................................................................. 21
18. Plants small; leaves imbricate; leaf cells narrowly rhombic; capsules rounded-ovoid............. 8. B. blindii
18. Plants large; leaves not imbricate; leaf cells long-rhomboidal; capsules ovoid to ellipsoidal................. 19
19. Leaves oblong-lanceolate to lanceolate, axillary gemmae usually absent; capsules cylindrical; apophyses thick, broader than urn...........................................................................................15. B. coronatum
19. Leaves ovate-lanceolate, axillary gemmae often present; capsules ovoid or shortly ellipsoidal; apophyses almost as broad as urn.............................................................................................20
20. Gemmae often with leaf primordia; apophyses scarcely shrunk when dry..................... 17. B. dichotomum
20. Gemmae without leaf primordia; apophyses shrunk when dry.......................28. B. pachytheca
21. Leaves oblong-lanceolate; leaf cells narrowly rhomboidal to linear.................................22
21. Leaves oblong-ovate; leaf cells rhombic to hexagonal..................................................25
22. Leaf margins distinctly recurved..................................................................31. B. paradoxum
22. Leaf margins plane, only slightly recurved......................................................................23
23. Costae percurrent.............................................................................................2. B. alpinum
23. Costae shortly excurrent......................................................................................24
24. Plants glossy, yellowish green; gemmae pyriform, mixed with rhizoids............................ 3. B. apiculatum
24. Plants not glossy, reddish; gemmae absent.....................................................40. B. thomsonii
25. Costae ending just below the apex, percurrent or shortly excurrent.................................26
25. Costae long-excurrent, ending in aristate awns............................................................28
26. Costae shortly excurrent; leaf cells linear-rhomboidal................................21. B. kashmirense
26. Costae ending below the apex or nearly percurrent; leaf cells rhombic to elongate-rhombic................. 27
27. Leaves broadly elliptical or spathulate, cucullate at apex; leaf cells lax and large.................. 13. B. cellulare
27. Leaves ovate or ovate-lanceolate, plane at apex; leaf cells thick-walled and small.............. 22. B. knowltonii
28. Leaf margins strongly recurved; leaf cells obliquely arranged...........................36. B. recurvulum
28. Leaf margins plane or only slightly recurved; leaf cells often longitudinally arranged............................ 29
29. Plants glossy, pale grayish...............................................................23. B. leptocaulon
29. Plants dull, brownish green..............................................................44. B. yuennanense
30. Plants small to medium-sized; leaves not forming rosettes; leaf margins nearly entire, serrulate near apex...........................................................................................................31
30. Plants large or robust; leaves forming rosettes; leaf margins serrate above middle................................. 43
31. Leaves sparse; setae 8–10 cm long; endostome segments longer than the teeth............26. B. longisetum
31. Leaves dense; setae less than 8 cm long; endostome segments shorter than or as long as the teeth.......32
32. Mouth of capsules and opercula large; endostome segments well developed..................................33
32. Mouth of capsules and opercula small; endostome segments reduced, adhered to the teeth................... 42
33. Leaf margins differentiated in the lower 1/2.........................................................34
33. Leaf margins differentiated throughout.................................................................35
34. Leaves ovate-lanceolate to lanceolate, acuminate at apex; leaf base not decurrent............ 14. B. clavatum
34. Leaves broadly ovate, apiculate at apex; leaf base decurrent.................................37. B. rutilans
35. Leaf margins serrate in the upper part; leaf cells 1–2׃1 (length׃width)................... 33. B. pseudotriquetrum
35. Leaf margins almost entire; leaf cells 2׃1 (length׃width)................................................36
36. Leaves oblong, oblong-ovate or spathulate......................................................12. B. capillare
36. Leaves ovate-lanceolate or lanceolate.............................................................37
37. Costae ending below the leaf apex or shortly excurrent; leaf apex cuspidate................38
37. Costae long-excurrent; leaf apex awned....................................................................41
38. Plants autoicous; cilia rudimentary; spores 30–36 µm in diameter............................. 34. B. purpurascens
38. Plants dioicous; cilia well developed; spores less than 25 µm in diameter.....................................39
39. Leaf margins strongly recurved; spores 8–10 μm in diameter.........................6. B. atrovirens
39. Leaf margins slightly recurved; spores 12–24 μm in diameter.....................................40
40. Leaf margins bordered by 1–2 rows of differentiated cells; all leaf cells uniform colored.......29. B. pallens
40. Leaf margins bordered by 2–4 rows of differentiated cells; basal leaf cells reddish brown.............. 42. B. turbinatum
41. Plants dioicous; capsules ellipsoidal or pyriform; spores 10–15 μm in diameter........... 10. B. caespiticium
41. Plants autoicous; capsules club-shaped; spores 16–22 μm in diameter..............25. B. lonchocaulon
42. Leaf margins bordered by 1 row of differentiated cells; basal marginal cells gradually becoming narrower
42. Leaf margins bordered by 2 rows of differentiated cells; basal marginal cells suddenly becoming wider..
...............................................................................................................4. B. arcticum
43. Leaf cells 35–65 µm long; costae shortly excurrent..........................................7. B. billarderi
43. Leaf cells 56–90 µm long; costae long-excurrent, ending in long, aristate awns........38. B. salakense