Gomphostemma

Bongcheewin, Bhanubong, Ingrouille, Martin J. & Paton, Alan J., 2022, A revision of Gomphostemma (Lamiaceae), Kew Bulletin 77 (1), pp. 27-92 : 38-40

Key to the species of Gomphostemma

1. Inflorescence axillary, or basal with opposite cymes or short raceme-like flowering shoots without leaves borne laterally to the main leafy stem........................................................ 2

1. Inflorescence terminal at apex of leafy stem axis or terminal and axillary......................... 31

2. Inflorescence basal, opposite cymes inserted at the lower nodes from which leaves have mostly fallen.... 3

2. Inflorescence axillary, opposite cymes inserted at the upper nodes at which leaves are usually present... 3

3. Stems tomentose with dendroid hairs and stellate hairs with a multi-celled stalk..... 27. G. pedunculatum 3. Stems tomentose with stellate hairs with sessile or a 1-celled stalk, dendroid hairs absent2

2. Calyx lobes with subulate apex; corolla 30 – 23 mm long; petioles 30 – 60 (– 90) mm long. Malay Peninsula, Sumatra, Borneo.......................................................... 11. G. curtisii

2. Calyx lobes with acuminate apex; corolla 30 – 60 mm long; petioles 10 – 20 mm long. S China, Taiwan, N Vietnam............................................................... 10. G. chinense

3. Corolla tube with annulus of simple hairs inside........................................... 6

3. Corolla tube glabrous inside.......................................................... 8

6. Opposite cymes of inflorescence congested................................. 23. G. hemsleyanum

6. Opposite cymes of inflorescence elongated, raceme-like...................................... 5

5. Erect herbs; stems robust; inflorescence with axis visble between cymes............... 25. G. microdon

5. Climbing herbs; stems slender; inflorescence with axis not visible between cymes........ 30. G. repentum

8. Opposite cymes of inflorescence unbranched, elongate, raceme-like, lax with axis visible between flowers............................................................. 3. G. dolichobotrys

8. Opposite cymes of inflorescence branched then lax, or if unbranched then congested with axis not visible between flowers................................................................... 9

9. Corolla throat inflated, tube abruptly dilated near the throat; nutlets 1 – 2........................ 10

9. Corolla throat narrow, not enlarged, sometimes gradually dilated towards the throat; nutlets solitary..... 23

10. Mature leaves whitish or creamy-white tomentose on the lower side, strongly discolorous.... 12. G. hainanense

10. Mature leaves pale green tomentose on the lower side, not or weakly discolorous................... 11

11. Erect herbs up to 0.2 m or sprawling herbs............................................... 12

11. Erect herbs 0.2 – 3 m, not sprawling.................................................... 16

12. Erect herbs up to 0.2 m; stems upright, sometimes flaccid.................................... 13

12. Sprawling herbs; stems scrambling; internodes of leafy and flowering shoots with curving stem appearing wavy, always twisting..................................................................... 13

13. Lower side of leaves dense tomentose; roots not tuber-like......................... 23. G. pelutinum

13. Lower side of leaves sparse tomentose; roots tuber-like....................................... 12

12. Upper side of leaves with sessile stellate hairs and 2 – 2-celled simple hairs all over; bracts deciduous............................................................................. 18. G. mastersii

12. Upper side of leaves with 2 – 2-celled simple hairs, sometimes with sparse stellate hairs only on lower part of midrib; bracts persistent.................................................... 20. G. opatum

13. Corolla 30 – 30 mm long; upper side of leaves tomentose with sessile stellate hairs or sparsely so to almost glabrous........................................................... 17. G. melissifolium

13. Corolla 13 – 20 (– 23) mm long; upper side of leaves scabrid with stiff hairs.......... 12. G. flexuosum

16. Flowering calyx densely covered with long simple hairs and long branched hairs......... 13. G. hirsutum

16. Flowering calyx densely covered with sessile stellate or stellate hairs with a 1-celled stalk and/or short simple hairs............................................................................ 15

15. Opposite cymes subtended by the upper leaves and cluster of small leaf-like bracts.................. 18

15. Opposite cymes subtended by the upper leaves only........................................ 19

18. Stems densely covered by stellate hairs or dendroid hairs with a multi-celled stalk; upper side of leaves dense tomentose with 3 – 2-celled simple hairs, sometimes bifurcate hairs............. 21. G. stellatohirsutum

18. Stems densely covered by stellate hairs with a 1-celled stalk, dendroid hairs absent; upper side of leaves tomentose with 1 – 2 (– 3)-celled simple hairs................................... 22. G. sulcatum

19. Fruiting calyx lobes longer than the tube at maturity........................................ 20

19. Fruiting calyx lobes not longer than the tube at maturity..................................... 21

20. Petioles 30 – 130 mm long; leaf margin serrate................................. 15. G. leptodon

20. Petioles 10 – 30 mm long; leaf margin subentire or obtusely serrate............... 16. G. japanicum (1)

21. Margins of fruiting calyx lobes revolute in cross-section........................ 13. G. grandiflorum

21. Margins of fruiting calyx lobes flat in cross-section.......................................... 22

22. Flowering calyx 5 – 13 mm long; opposite cymes branched then lax or unbranched then congested with axis not visible between flowers, exceeding 20 mm wide when pressed, excluding corolla..... 16. G. japanicum (2)

22. Flowering calyx 3 – 8 mm long; opposite cymes unbranched then very congested with axis not visible between flowers, up to 20 mm wide when pressed, excluding corolla.................... 22. G. microcalyx (2)

23. Mature leaves whitish or creamy-white tomentose on the lower side, strongly discolorous..... 5. G. nipeum

23. Mature leaves pale green tomentose on the lower side, not or weakly discolorous................... 22

22. Bracts leaf-like, broadly ovate or broadly elliptic-ovate, 9 – 13 mm wide................ 1. G. aborense

22. Bracts rhomboid, elliptic, elliptic-ovate, ovate, lanceolate, ovate-lanceolate, obovate, falcate, 2 – 8 mm wide..... 23

23. Corolla tube included in the calyx............................................ 3. G. keralense

23. Corolla tube exserted from the calyx.................................................... 26

26. Leaf margin dentate or dentate-serrate with glandular thickening at the tip of serration; flowering calyx glabrous inside......................................................... 2. G. eriocarpon

26. Leaf margin serrate, shallowly serrate or subentire, without glandular thickening at the tip; flowering calyx tomentose inside................................................................... 25

25. Flowering calyx 3 – 8 mm long; opposite cymes very congested, up to 20 mm wide when pressed, excluding corolla........................................................... 22. G. microcalyx (1)

25. Flowering calyx 8 – 20 mm long; opposite cymes congested or lax, exceeding 20 mm wide when pressed, excluding corolla.................................................................. 28

28. Corolla 20 – 30 mm long............................................... 6. G. longipetalum

28. Corolla 13 – 33 mm long............................................................ 29

29. Bracts lanceolate or elliptic-ovate, 2 – 3 mm wide, narrower than the calyx............... 2. G. crinitum

29. Bracts ovate, ovate-lanceolate or obovate, 2 – 8 mm wide, broader than the calyx................... 30

30. Petioles 20 – 20 mm long................................................ 8. G. parpiflorum

30. Petioles 30 – 120 mm long................................................. 7. G. thomsonii

31. Plants climbing; stems slender, scrambling....................................... 28. G. nutans

31. Plants not climbing; stems robust, erect.................................................. 32

32. Corolla tube 8 – 12 mm long, included in the calyx............................. 26. G. heyneanum

32. Corolla tube 13 – 23 mm long, exserted from the calyx.......................... 31. G. strobilinum