Lasianthus species

Dang, Van-Son & Naiki, Akiyo, 2023, A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam, Phytotaxa 581 (1), pp. 1921-1935 : 1921-1935

Key to Lasianthus species in Vietnam

1. Bracts conspicuous, more than 3 mm long ........................................................................................................................................2

- Bracts absent or inconspicuous, usually less than 3 mm long .........................................................................................................19

2 Inflorescence stalked, with peduncles more than 2 mm long ............................................................................................................3

- Inflorescence sessile ..........................................................................................................................................................................4

3. Branches tomentose; leaf blade up to 15 cm long, secondary veins 7–8 on each side of midrib ...............................10. L.capitatus

- Branches villous; leaf blade up to 21 cm long, secondary veins up to 12 on each side of midrib ........................ 58. L. rhinocerotis

4. Bracts leaf-like ...................................................................................................................................................................................5

- Bracts linear, filiform, subulate, lanceolate or ovate .........................................................................................................................6

5. Stipules 6–7.5 mm long; calyx and corolla with lobes 5; pyrenes 5 ............................................................................29. L. hirsutus

- Stipules 8–10 mm long; calyx and corolla with lobes 4; pyrenes 4 .................................................................... 55. L. phamhoangii

6. Secondary veins of more than 13 on each side of midrib ..................................................................................................................7

- Secondary veins less than 13 on each side of midrib ........................................................................................................................8

7. Petioles 1–3 mm long; bracts 8 mm long .............................................................................................................. 7. L. cambodianus

- Petioles 15–25 mm long; bracts 15–18 mm long ......................................................................................................26. L. giganteus

8. Fruits with 4 pyrenes .........................................................................................................................................................................9

- Fruits with more than 4 pyrenes ......................................................................................................................................................11

9. Bracts 8–10 mm long; petioles 2–3 mm long ..............................................................................................................45. L. lecomtei

- Bracts less than 8 mm long; petioles more than 3 mm long ............................................................................................................10

10. Leaf blade 9–16 cm long; branches appressed-pubescent .................................................................................25. L. foxworthyanus

- Leaf blade 4.5–10 cm long; branches tomentose to strigose ......................................................................................62. L. schmidtii

11. Branches glabrous or glabrescent ....................................................................................................................................................12

- Branches hairy .................................................................................................................................................................................13

12. Petioles up to 15 mm long; stipules 5.5–6.5 mm long; leaf blade 6–8 cm wide ..................................................... 4. L. bidoupensis

- Petioles up to 10 mm long; stipules 3–5 mm long; leaf blade 2.5–6 cm wide............................................................ 33. L. inodorus

13. Stipules 15–17 mm long ..........................................................................................................................................19. L. eberhardtii

- Stipules less than 15 mm long .........................................................................................................................................................14

14. Base of leaf blade cordate or rarely rounded ..............................................................................................................2. L. attenuatus

- Base of leaf blade cuneate, acute or obtuse .....................................................................................................................................15

15. Leaf blade 12–20 cm long; petioles more than 5 mm long .............................................................................................................16

- Leaf blade less than 12 cm long; petioles less than 5 mm long ......................................................................................................17

16. Corolla 5–6 mm long; bracts up to 5 mm long ....................................................................................................14. L. chrysoneurus

- Corolla 10 mm long; bracts up to 20 mm long ....................................................................................................... 63. L. sikkimensis

17. Calyx tube 1.5 mm long, lobes 6 and 1 mm long ...................................................................................................... 1. L. annamicus

- Calyx tube 2–3 mm long, lobes 5 and 3–4 mm long .......................................................................................................................18

18. Petioles 2 mm long; stipules 4–5 mm long .........................................................................................................20. L. elevatineurus

- Petioles 4–5 mm long; stipules 2–3.5 mm long ................................................................................................. 41. L. lamdongensis

19. Inflorescence conspicuously pedunculate .......................................................................................................................................20

- Inflorescence sessile ........................................................................................................................................................................29

20. Bracts 1.5–3 mm long ......................................................................................................................................................................21

- Bracts less than 1.5 mm long ...........................................................................................................................................................23

21. Leaf blade 16–25 cm long; calyx lobes 4; fruits with 4 pyrenes ................................................................... 38. L. konchurangensis

- Leaf blade less than 16 cm long; calyx lobes 5; fruits with 5 pyrenes ............................................................................................22

22. Peduncles 1.5–5 mm long; calyx lobes 1–1.5 mm long ......................................................................................... 48. L. micranthus

- Peduncles 10–35 mm long; calyx lobes 2–3 mm long ......................................................................................... 66. L. tamdaoensis

23. Bracts 1 mm long; peduncles 1–2 mm long ....................................................................................................................................24

- Bracts inconspicuous; peduncles more than 2 mm long .................................................................................................................25

24. Secondary veins 5–7 mm long; stipules up to 3 mm long .........................................................................................34. L. japonicus - Secondary veins 8–10 mm long; stipules up to 1 mm long ..................................................................................72. L. viridiramulis

25. Calyx lobes 4 .......................................................................................................................................................... 28. L. hatinhensis

- Calyx lobes 5 ...................................................................................................................................................................................26

26. Petioles 9–12 mm long; calyx lobes to 0.25 mm long .........................................................................................22. L. foetidissimus

- Petioles less than 9 mm long; calyx lobes more than 0.5 mm long .................................................................................................27

27. Calyx lobes 1.5–2 mm long; fruits with 5 pyrenes ....................................................................................................59. L. sapaensis

- Calyx lobes less than 1 mm long; fruits with 4 pyrenes ..................................................................................................................28

28. Petioles 0.5–2 mm long; peduncles up to 15 mm long; fruits ovoid, black ................................................................... 5. L. biflorus

- Petioles 6–10 mm long; peduncles up to 5 mm long; fruits ellipsoid, blue ........................................................21. L. fansipanensis

29. Bracts 1–3 mm long .........................................................................................................................................................................30

- Bracts less than 1, inconspicuous or absent .....................................................................................................................................43

30. Petioles 10–15 mm long ..................................................................................................................................................................31

- Petioles less than 10 mm long .........................................................................................................................................................33

31. Leaf blade 15–20 mm long; calyx lobes 2.5–4 mm long ............................................................................................. 75. L. yersinii

- Leaf blade less than 15 mm long; calyx lobes less than 2.5 mm long ............................................................................................32

32. Corolla tube 3 mm long; fruits ovoid to ellipsoid, orange, pyrenes 4 .................................................................... 31. L. honbaensis

- Corolla tube 5–6.5 mm long; fruits ovoid, blue, pyrenes 5 ......................................................................................50. L. nghiasonii

33. Branches and petioles glabrous .......................................................................................................................................................34

- Branches and petioles hairy .............................................................................................................................................................35

34. Stipules 1–1.5 mm long; leaf blade 5–7 mm long; fruits subglobose, pyrenes 4 .................................................53. L. nuichuaensis

- Stipules 2–3.5 mm long; leaf blade 8–16 mm long; fruits ovoid, pyrenes 5 ............................................................... 74. L. yaharae

35. Calyx lobes 5–6 mm long; fruits 8–10 mm in diam. .......................................................................................................... 12. L. chii

- Calyx lobes less than 5 mm long; fruits less than 8 mm in diam. ...................................................................................................36

36. Petioles 6–10 mm long; calyx tube 2.5–4.5 mm long .....................................................................................................................37

- Petioles less than 6 mm long; calyx tube less than 2.5 mm long ....................................................................................................38

37. Calyx lobes 4–5; fruits with 4 pyrenes ..................................................................................................................... 27. L. globularis

- Calyx lobes 6; fruits with 6 pyrenes ....................................................................................................................73. L. vuquangensis

38. Calyx tube 0.5 mm long and lobes 0.2 mm long .........................................................................................................61. L. saxorum

- Calyx tube more than 1 mm long and lobes 1.5 mm long ...............................................................................................................39

39. Branches densely villous .................................................................................................................................................................40

- Branches glabrous to sparsely strigose or pubescent ......................................................................................................................41

40. Leaf blade 12–14 mm long; calyx lobes less than 2.5 mm long .......................................................................36. L. khanhhoaensis

- Leaf blade 8–9.5 mm long; calyx lobes more than 2.5 mm long ............................................................... 65. L. stephanocalycinus

41. Leaf blade ovate-oblong to ovate-elliptic; bracts strigose ....................................................................................39. L. komtumensis

- Leaf blade elliptic; bracts tomentose or pubescent ..........................................................................................................................42

42. Calyx widely campanulate; fruits 3–4 mm in diam. ............................................................................................. 16. L. dakglaiensis

- Calyx cupulate; fruits 5 mm in diam. .................................................................................................................52. L. nhatrangensis

43. Secondary veins of more than 7 on each side of midrib ..................................................................................................................44

- Secondary veins less than 7 on each side of midrib ........................................................................................................................55

44. Calyx lobes shorter than tube or as long as tube .............................................................................................................................45

- Calyx lobes longer than tube ...........................................................................................................................................................50

45. Stipules more than 4 mm long; secondary veins less than 9 on each side of midrib ......................................................................46

- Stipules less than 3 mm long; secondary veins more than 9 on each side of midrib ......................................................................48

46. Leaf blade ovate to ovate-lanceolate, glabrous; calyx tube 1 mm long ................................................................... 17. L. dalatensis

- Leaf blade oblong to elliptic-oblong, hirsute or strigillose abaxially; calyx tube 2–3 mm long......................................................47

47. Corolla 6–8 mm long, lobes 4; fruits 5–6 mm in diam. ..................................................................................... 69. L. trichophlebus

- Corolla 10–12 mm long, lobes 5; fruits up to 10 mm in diam. ............................................................................. 70. L. verticillatus

48. Calyx tube 1.5–2.5 mm long; secondary veins more than 10 on each side of midrib ................................................13. L. chinensis

- Calyx tube less than 1.5 mm long; secondary veins less than 10 on each side of midrib ...............................................................49

49. Leaf blade less than 13 cm long; fruits with 2 pyrenes ......................................................................................40. L. lacduongensis

- Leaf blade more than 15 cm long; fruits with 5 pyrenes ..........................................................................................42. L. lancifolius

50. Calyx lobes 8–14 mm long ..............................................................................................................................................................51

- Calyx lobes less than 5 mm long .....................................................................................................................................................52

51. Petioles more than 12 mm long; stipules 3 mm long; calyx tube less than 3 mm long ............................................11. L. chevalieri

- Petioles less than 10 mm long; stipules 4–5 mm long; calyx tube more than 4 mm long ...............................18. L. dienkhanhensis

52. Secondary veins 14–15 on each side of midrib; tertiary leaf veins reticulate ....................................................... 57. L. repoeuensis

- Secondary veins less than 10 on each side of midrib; tertiary leaf veins parallel or subparallel ....................................................53

53. Petioles more than 6 mm long; calyx tube 2–2.5 mm long ....................................................................................8. L. camlamensis

- Petioles less thang 4 mm long; calyx tube less than 2 mm long .....................................................................................................54

54. Branches villous; leaf blade lanceolate; calyx with lobes 6 ......................................................................................... 43. L. larsenii

- Branches tomentose; leaf blade elliptic-oblong to oblong-lanceolate; calyx with lobes 5 ................................ 51. L. ngoclinhensis

55. Calyx tube longer lobes or as long as lobes ....................................................................................................................................56

- Calyx tube shorter lobes ..................................................................................................................................................................67

56. Calyx tube 2–5 mm long; bracts 0.5–1 mm long .............................................................................................................................57

- Calyx tube less than 2 mm long; bracts inconspicuous, minute, absent or very small ...................................................................58

57. Leaf blade oblong-lanceolate; calyx with lobes 5; fruits 4–5 mm in diam., yellowish-white .............................71. L. vietnamensis

- Leaf blade elliptic-ovate or oblong; calyx with lobes 6; fruits 6–7 mm in diam., blue .................................................. 49. L. naikii 58. Calyx with lobes 3 ...............................................................................................................................................60. L. saprosmoides

- Calyx with lobes 4–5, 5–6 or 5 ........................................................................................................................................................59

59. Leaf blade less than 2 cm wide; petioles 2–5 mm long ...................................................................................................................60

- Leaf blade more than 2 cm wide; petioles more than 5 mm long ...................................................................................................62

60. Calyx with lobes 4; petioles 2–3 mm long ...........................................................................................................64. L. sonlangensis

- Calyx with lobes 5; petioles more than 3 mm long .........................................................................................................................61

61. Leaf blade oblong-lanceolate, coriaceous ...................................................................................................................6. L. caeruleus

- Leaf blade linear-lanceolate, subcoriaceous ...................................................................................................................56. L. pierrei

62. Corolla tube 10–15 mm long; leaf blade 4–8 cm long ...............................................................................................68. L. thuyanae

- Corolla tube less than 7 mm long; leaf blade more than 8 cm long ................................................................................................63

63. Leaf blade 1.5–2.5 cm wide; stipules 1.5–2 mm long .................................................................................................. 9. L. candidus

- Leaf blade more than 2.5 cm wide; stipules less than 1.5 mm long ................................................................................................64

64. Petioles glabrous, 8–10 mm long; fruits with 2(–4) pyrenes ...........................................................................................................65

- Petioles densely pubescent, hirsute or strigose, 4–7 mm long; fruits with 5 pyrenes .....................................................................66

65. Calyx 1–1.2 mm long; petioles less than 10 mm long; leaf blade less than 13 cm long ............................... 67. L. thuathienhuensis

- Calyx 2–3 mm long; petioles more than 11 mm long; leaf blade more than 15 cm long .......................................35. L. kbangensis

66. Branches brown-villous; stipules less than 1 mm long; calyx lobes less than 1.5 mm long .................................... 30. L. hispidulus

- Branches pubescent; stipules more than 1.2 mm long; calyx lobes more than 1.7 mm long .............................. 32. L. hongiaoensis

67. Secondary veins 3–4 on each side of midrib .................................................................................................................47. L. lucidus

- Secondary veins of more than 4 on each side of midrib ..................................................................................................................68

68. Petioles 10–15 mm long; leaf blade 5–7 cm wide ...................................................................................................... 44. L. latifolius

- Petioles less than 9 mm long; leaf blade less than 4 cm wide .........................................................................................................69

69. Branches and leaf blade abaxially glabrous; tertiary leaf veins subreticulate ......................................................54. L. oblongilobus

- Branches and leaf blade abaxially hairy; tertiary leaf veins parallel or subparallel ........................................................................70

70. Leaf blade less than 2 cm wide; stipules 0.5 mm long ...........................................................................................46. L. longissimus

- Leaf blade more than 2 cm wide; stipules more than 0.8 mm long .................................................................................................71

71. Secondary veins 6–7 on each side of midrib; stipules villous, 2 mm long ........................................................... 24. L. formosensis

- Secondary veins less than 6 on each side of midrib; stipules pubescent or strigose, less than 1.8 mm long ..................................72

72. Branches and petioles densely villous; calyx lobes divided nearly to base .................................................................. 15. L. curtisii

- Branches and petioles appressed-pubescent or strigose; calyx lobes not divided nearly to base ....................................................73

73. Calyx tube 1.5–2 mm long, calyx lobes 2.5–3 mm long; fruits 4 in diam. ......................................................37. L. khanhvinhensis

- Calyx tube less than 1.5 mm long, calyx lobes less than 2.5 mm long; fruits 5–6 mm in diam. .....................................................74

74. Leaf blade more than 10 mm long; calyx lobes 1.5–2.5 mm long; fruits hemispheric, orange .............................3. L. bachmaensis

- Leaf blade less than 8 mm long; calyx lobes 1–1.5 mm long; fruits globose or subglobose, blue ..................................23. L. fordii