Lasianthus, Jack, 1823

Napiroon, Tiwtawat, Chayamarit, Kongkanda, Dawson, Sally, Till, Walter & Balslev, Henrik, 2020, A synopsis of Lasianthus (Lasiantheae, Rubiaceae) in Thailand and two additional new species, Phytotaxa 439 (1), pp. 1-38 : 3-5

Key to the species of Lasianthus in Thailand

1. Cymes sessile or subsessile ............................................................................................................................................................. 2.

-. Cymes conspicuously pedunculate ................................................................................................................................................ 58.

2. Flowers obviously pedicellate ......................................................................................................................................................... 3.

-. Flowers sessile ................................................................................................................................................................................. 4.

3. Leaves blade narrowly oblong-lanceolate, 9–12 × 2–3 cm, lateral veins 6–7 pairs; flowers pedicels 3 mm long, calyx cupular, calyx limb truncate or nearly entire .................................................................................................................................... 39. L. oblongus

-. Leaves blade elliptic to lanceolate, 21–31 × 9–11 cm, lateral veins 16–17 pairs; flowers pedicels less than 1 mm long, calyx tube campanulate, calyx limb triangular .......................................................................................................................... 22. L. giganteus

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

-. Bracts filiform, linear, subulate or lanceolate .................................................................................................................................. 7.

5. Branches hirsute; leaf blade oblong, coriaceous, hirsute ............................................................................................. 24. L. hirsutus

-. Branches tomentose; leaf blade elliptic-oblong to oblanceolate-oblong membranaceous, tomentose .............................................6.

6. Bracteoles numerous; calyx campanulate, tomentose; drupes ovoid, sparely pilose, 4 pyrenes.......................... 15. L. cyanocarpus

-. Bracteoles absent; calyx obconical, densely hirsute; drupes elliptic, base narrow, hirsute, 5 pyrenes ............................. 45. L. puffii

7. Stipules obviously large and covering the cymes....................................................................................................... 59. L. stipularis

-. Stipules not covering the cymes ........................................................................................................................................................8.

8. Bracts filiform ...................................................................................................................................................................................9.

-. Bracts linear, subulate or lanceolate ................................................................................................................................................10.

9. Nerves 9–15 pairs; calyx tubular, pilose ........................................................................................................................ 43. L. pilosus

-. Nerves 7–8 pairs; calyx cupular, strigose....................................................................................................................67. L. yalaensis

10. Leaf blade membranaceous, base oblique or slightly cordate.....................................................................................3. L. attenuatus

-. Leaf blade chartaceous or coriaceous, base not oblique..................................................................................................................11.

11. Stipules not persistent......................................................................................................................................................................12.

-. Stipules persistent............................................................................................................................................................................14.

12. Bracts more than 1 cm and up to 2 cm long; drupes ellipsoid, glabrous................................................................. 57. L. sikkimensis

-. Bracts 5–8 mm long; fruits subglobose, not glabrous .....................................................................................................................13.

13. Drupes with 5 pyrenes, tomentose..............................................................................................................................13. L. coronatus

-. Drupes with 4 pyrenes, verrucose ................................................................................................................................... 52. L. ridleyi

14. Stipules broadly triangular, 7–8 mm long ...................................................................................................................17. L. ellipticus

-. Stipules triangular or lanceolate, up to 5 mm long..........................................................................................................................15.

15. Branches and leaves glabrous; bracts orbicular........................................................................................................... 27. L. inodorus

-. Branches and leaves not glabrous; bracts not orbicular ..................................................................................................................16.

16. Lateral nerves faint beneath; drupe obviously tetragonal......................................................................................... 62. L. tetragonus

-. Lateral nerves conspicuous beneath; drupe globose, subglobose or ellipsoid ................................................................................17.

17. Fruits with 4 pyrenes .......................................................................................................................................................................18.

-. Fruits mostly with more than 4 pyrenes ..........................................................................................................................................20.

18. Branches and leaves pubescent beneath; fruits pubescent ..............................................................................................................19.

-. Branches and leaves tomentose beneath; drupes tomentose .......................................................................................56. L. schmidtii

19. Bracts linear; drupe globose or subglobose, 5 mm or more diam. when mature ............................................................ 48. L. rabilii

-. Bracts lanceolate; drupe subglobose to ellipsoid, less than 5 mm diam. when mature......................................21. L. foxworthyanus

20. Bracts relatively large, persistent.....................................................................................................................................................21.

-. Bracts not conspicuous or absent ....................................................................................................................................................25.

21. Fruits with 8 pyrenes ....................................................................................................................................................1. L. appressus

-. Fruits with less than 8 pyrenes but more than 4 pyrenes.................................................................................................................22.

22. Bracts linear, up to 1.7 cm long..................................................................................................................................31. L. lineolatus

-. Bracts not linear, up to 5 mm long ..................................................................................................................................................23.

23. Branches appressed pubescent; leaf base cuneate, appressed pubescent on nerves beneath ..........................................................24.

-. Branches villose; leaf base obtuse or rounded, villose on nerves beneath.................................................................... 2. L. aristatus

24. Drupes subglobose, tomentose .................................................................................................................................... 39. L. obscurus

-. Drupes subglobose, subglabrous or pubescent.......................................................................................................9. L. chrysoneurus

25. Calyx lobes linear, 1–1.5 cm long ............................................................................................................................... 7. L. chevalieri

-. Calyx lobe not linear, less than 1 cm long.......................................................................................................................................26.

26. Calyx cupular, calyx lobes broadly triangular up to 1 mm long ................................................................... 58. L. sithammaratensis

-. Calyx campanulate, obconical or tubular truncate ..........................................................................................................................27.

27. Calyx lobes longer than or equal to tube ........................................................................................................................................ 28.

-. Calyx lobes shorter than tube ..........................................................................................................................................................35.

28. Calyx obconical, calyx lobe cleft deeply to the base...................................................................................................... 14. L. curtisii

-. Calyx campanulate, calyx lobe not cleft to the base .......................................................................................................................29.

29. Leaves usually small, less than 10 cm long, lateral nerves 5 pairs or less ......................................................................................30.

-. Leaves usually more than 10 cm long, lateral nerves more than 5 pairs.........................................................................................31.

30. Leaf base cuneate, petioles 5-8 mm long; calyx lobe linear or linear- lanceolate .........................................................34. L. lucidus

-. Leaf base rounded or subrounded, petiole 2-3 mm long; calyx lobe triangular..................................................... 54. L.sarmentosus

31. Bracts absent or inconspicuous .......................................................................................................................................................32.

-. Bracts present ..................................................................................................................................................................................35.

32. Lateral nerves 8 or more pairs, calyx small 2 mm long ...........................................................................................41. L. parviflorus

-. Lateral nerves less than 7 pairs, calyx 4–5 mm long.......................................................................................................................34.

33. Branches hirsute; stipules subulate; calyx hirsute ....................................................................................................18. L. flavi-hirtus

-. Branches villous; stipules triangular; calyx villose ................................................................................................ 20. L. formosensis

34. Drupes with 5 pyrenes................................................................................................................................................. 32. L. loeiensis

-. Drupes with 6 pyrenes................................................................................................................................................53. L. roosianus

35. Tertiary veins conspicuously reticulate ...........................................................................................................................................36.

-. Tertiary veins conspicuously paralle ...............................................................................................................................................42.

36. Branches and leaves densely pubescent; leaves narrowly oblong..............................................................................6. L. chartaceus -. Branches and leaves glabrous; leaves oblong-lanceolate or oblanceolate ......................................................................................37.

37. Stipules small 3 mm long, lanceolate, lateral nerves 8–9 pairs................................................................................11. L. conspicuus

-. Stipules 5 or more than 5 mm long, oblong-triangular, lateral nerves 11–16 pairs.........................................................................38.

38. Calyx truncate or subtruncate..........................................................................................................................................................39.

-. Calyx not truncate or subtruncate....................................................................................................................................................40.

39. Stipules triangular-subulate or narrow triangular; lateral nerves more than 10 pairs .....................................................................41.

-. Stipules broad triangular; lateral nerves 7–8 pairs ............................................................................................. 46. L. purpureocalyx

40. Lateral nerves 11–12 pairs; petiole 1–1.5 cm long.................................................................................................... 60. L. subaureus

-. Lateral nerves 14–16 pairs; petiole 5–8 mm long .................................................................................................. 49. L. repoeuensis

41. Calyx campanulate-cupular, puberulous, 5 lobes with minutely triangular; drupes glabrous................................38. L. malaccensis

-. Calyx elongate campanulate, puberulous, 4–6 triangular-ovate or orbicular reflexed lobes; drupes pubescent ..........8. L. chinensis

42. Stipule large 6–10 mm long, coriaceous or subcoriaceous .............................................................................................................43.

-. Stipules less than 5 mm long, chartaceous ......................................................................................................................................46.

43. Stipules surface glabrous; calyx limb truncate................................................................................................................. 23. L. helfer

-. Stipules surface with hairs; calyx limb not truncate........................................................................................................................44.

44. Lateral nerves 7–9 pairs; petioles 5–8 mm long; calyx campanulate.................................................................. 65. L. trichophlebus

-. Lateral nerves more than 10 pairs; petioles 2–4 mm long; calyx tubular .......................................................................................45.

45. Calyx hirsute; drupes with 4 pyrenes, pilose............................................................................................................. 35. L. maculatus

-. Calyx pilose; drupe with 5 pyrenes, hirsute ............................................................................................................ 37. L. marginatus

46. Branches conspicuously tomentose......................................................................................................................... 63. L. tomentosus

-. Branches pubescent or puberulous ..................................................................................................................................................47.

47. Leaves more than 15 cm long..........................................................................................................................................................48.

-. Leaves less than 13 cm long............................................................................................................................................................53.

48. Calyx cupular, limb truncate ...........................................................................................................................................................49.

-. Calyx not cupular, limb not truncate ...............................................................................................................................................50.

49. Calyx mouth wide, unfolded; drupes with 10 pyrenes............................................................................................. 42. L. perakensis

-. Calyx mouth not wide; drupes with 4–5 pyrenes ................................................................................................... 66. L. verticillatus

50. Drupe conspicuously oblique-elliptic, verrucose ..................................................................................................... 50. L. reticulatus

-. Drupes globose or subglobose, not oblique, pubescent...................................................................................................................51.

51. Drupes fusiform, pyrenes 4 ........................................................................................................................................61. L. subcalvus

-. Drupes globose, pyrene 5 or 6.........................................................................................................................................................52.

52. Lateral nerves 8–9 pairs; calyx puberulous...............................................................................................................30. L. lancifolius

-. Lateral nerves 6‒8 pairs; calyx glabrous....................................................................................................................... 26. L. hookeri

53. Drupes with 2–4 pyrenes.................................................................................................................................................................54.

-. Drupes with 5–6 pyrenes.................................................................................................................................................................55.

54. Leaves blade usually obovate or oblong; drupe globose with 3 pyrenes; calyx limb ovate-lanceolate................. 40. L. oligoneurus

-. Leaf blade usually lanceolate to oblong-lanceolate; drupe ellipsoid usually with 4 pyrenes; calyx limb hemispherical.................... ..................................................................................................................................................................................12. L. constrictus

55. Branches usually glabrous; corolla glabrous on the outside .............................................................................................19. L. fordii

-. Branches usually pubescent or villous; corolla not glabrous on the outside...................................................................................56.

56. Drupes hirsute; corolla floccose inside................................................................................................................... 16. L. ellipsoideus

-. Drupes pubescent or puberulous; corolla not floccose inside .........................................................................................................57.

57. Corolla pilose on the outside, villous inside.............................................................................................................. 25. L. hispidulus

-. Corolla pubescent on the outside, pilose inside........................................................................................................... 55. L. saxorum

58. Flowers pedicellate or subsessile.....................................................................................................................................................59.

-. Flowers sessile.................................................................................................................................................................................62.

59. Inflorescences usually with long peduncles, 4–10 cm long ........................................................................ 33. L. longipudunculatus

-. Inflorescences with peduncles 4 cm or less long.............................................................................................................................60.

60. Bracts absent; calyx 2 mm long.......................................................................................................................... 10. L. congesticymus

-. Bracts present; calyx 3.5–5 mm long ..............................................................................................................................................61.

61. Peduncle 1.5 cm long or less, hirsute ...............................................................................................................................................62

-. Peduncle 2.5 cm long or over, glabrous ................................................................................................................... 28. L. kailarsenii

62. Calyx obconical, deeply lobed ................................................................................................................................... 29. L.krabiensis

-. Calyx cupular, minutely toothed ...........................................................................................................................67. L. viridiramulis

63. Peduncles, 1–4 cm long....................................................................................................................................................................63

-. Peduncles, <1 cm long.....................................................................................................................................................................64

64. Leaves subrhomboid or elliptic-obovate, mostly 2‒2.5 cm long .................................................................................... 5. L. biflorus

-. Leaves oblong-lanceolate, ovate-lanceolate or elliptic, more than 4 cm long .................................................................................65

65. Bracts inconspicuous, bracteoles none; drupes globose, puberulus.......................................................................... 44. L. puberulus

-. Bracts conspicuous, bracteoles numerous, drupes ovoid, tomentose..............................................................62. L. tennissarimensis

66. Lateral veins 5–6 pairs; calyx hirsute...................................................................................................................... 38. L. micranthus

-. Lateral veins 8–12 pairs; calyx sparsely pilose ................................................................................................................................66

67. Branches and leaves sparsely pilose; drupes with 4 pyrenes...........................................................................................4. L. bicolor

-. Branches and leaves brown villous; drupes with 5 pyrenes................................................................................... 51. L. rhinocerotis