Pogostemon

YAO, GANG, DENG, YUN-FEI & GE, XUE-JUN, 2015, A Taxonomic Revision Of Pogostemon (Lamiaceae) From China, Phytotaxa 200 (1), pp. 448-450 : 448-450

Key to the species of Pogostemon in China

1. Leaves opposite .................................................................................................................................................................... 2

- Leaves in whorls of 3 or more, or sometimes opposite simultaneously ............................................................................. 18

2. Perennial herbs or subshrubs; inflorescence a terminal spike, with more than two lateral branches .................................. 3

- Annual herbs; inflorescence a single terminal spike, or sometimes with two lateral branches .......................................... 14

3. Calyx <3 mm long; corolla shorter or slightly longer than the calyx ......................................................... P. amaranthoides

- Calyx ≥ 3mm long; corolla much longer than calyx and exserted evidently from calyx ..................................................... 4

4. Cultivated plant; calyx 6–8 mm long ......................................................................................................................... P. cablin

- Wild plant; calyx 3–5 mm long ............................................................................................................................................ 5

5. Leaf blade narrowly elliptic, or lanceolate ............................................................................................................................ 6

- Leaf blade ovate, elliptic, or broadly ovate .......................................................................................................................... 7

6. Calyx tubular, 3.5–4.5 mm long, teeth 1/5–1/4 as long as the calyx tube; corolla to 7–8 mm long .................. P. dielsianus

- Calyx campanulate, 3–3.5 mm long, teeth 1/3–1/2 as long as the calyx tube; corolla ca. 4.5 mm long ....... P. elsholtzioides

7. Leaf margin incised-serrate or double incised-serrate .......................................................................................................... 8

- Leaf margin double serrate, double crenate-serrate, or double dentate ................................................................................ 9

8. Stems pubescent, glabrescent; leaves glabrous or sparsely strigulose; bracts and bracteoles linear-lanceolate to linear; calyx teeth ca. 1/2 as long as the calyx tube ..................................................................................................... P. formosanus

- Stems and leaves evidently setose; bracts and bracteoles oblong-lanceolate to broadly lanceolate; calyx teeth ca. 1/3 as long as the calyx tube ................................................................................................................................... P. xanthiiphyllus

9. Spikes of inflorescence very short, 0.7–3.5 cm long ......................................................................................... P. parviflorus

- Spikes of inflorescence usually longer than 5 cm, and sometimes longer than 10 cm ........................................................ 10

10. Calyx tube glandular in flower.............................................................................................................................................11

- Calyx tube without glands in flower .................................................................................................................................... 12

11. Calyx subtubular, teeth narrowly triangular, subequal or 2 shorter, ca. 1/3 as long as calyx tube ....................... P. chinensis

- Calyx infundibuliform, teeth triangular, equal, 1/3–1/2 as long as calyx tube ............................................. P. septentrionalis

12. Lateral veins of leaves 3 pairs; flowers bluish; calyx teeth 1/3–1/2 as long as the calyx tube; stigma lobes 2–2.5 mm long ................................................................................................................................................................................ P. latifolius

- Lateral veins of leaves 4–6 pairs; flowers white, pink or purplish; calyx teeth 1/3 as long as the calyx tube; stigma lobes less than 1.5 mm long ......................................................................................................................................................... 13

13. Stems, abaxial leaf surface, bracteoles, and outer part of calyx subglabrous or sparsely pubescent ...... P. glaber var. glaber

- Stems, abaxial leaf surface, bracteoles, and outer part of calyx villous ..................................... P. glaber var. tsingpingensis

14. Spike very loose, unbranched or sometimes with two lateral branches; calyx longer than 2 mm, 10-veined; calyx teeth usually awl-shaped in fruit; throat of calyx tube ringed by hairs ............................................................................................. 15

- Spike compact, simple; calyx less than 2 mm long, 5-veined; calyx teeth triangular or broadly triangular in fruit; throat of calyx tube not ringed by hairs ............................................................................................................................................. 17

15. Calyx 4–6 mm long; corolla to 7.5 mm long ........................................................................................................ P. fraternus

- Calyx ≤ 4 mm long; corolla less than 5 mm long ............................................................................................................... 16

16. Lateral veins 3–5 pairs; calyx 3–4 mm long; calyx tubular-campanulate in fruit; stamens and style much exserted from corolla; filaments sparsely bearded at middle ............................................................................................. P. brachystachyus

- Lateral veins 5–9 pairs; calyx 2–3 mm long; calyx urceolate-campulate in fruit; stamens and style not exserted from corolla; filaments glabrous ............................................................................................................................. P. hispidocalyx

17. Stems and leaves yellow strigose; petiole of leaves usually longer than 1 cm, and up to 2 cm long; leaf margin crenate to double crenate; base of leaves broadly cuneate to cuneate .................................................................................. P. barbatus

- Stems and leaves black or dark brown strigose; petiole of leaves subsessile or less than 1 cm long; leaf margin serrate or double serrate; base of leaves rounded to shallowly cordate, rarely cuneate .................................................. P. auricularius

18. Leaves opposite or verticillate, with a short petiole............................................................................................................ 19

- Leaves verticillate, sessile ................................................................................................................................................... 20

19. Leaf blade falcate ..................................................................................................................................................... P. falcatus

- Leaf blade linear or lanceolate .......................................................................................................................... P. quadrifolius

20. Stem and leaf blade hairy evidently ................................................................................................................................... 21

- Stem and leaf blade glabrous ............................................................................................................................................. 23

21. Stems pubescent, rust colored; calyx 2.5–2.8 mm long; corolla 4–4.2 mm long ................................................... P. linearis

- Stems strigose; calyx <2mm long; corolla <3 mm long .................................................................................................. 22

22. Leaf margin entire; blade yellow or brown strigose ............................................................................................. P. cruciatus

- Leaf margin with remotely shallow serrate; blade grey ciliate ........................................................................ P. szemaoensis

6 • Phytotaxa 200 (1) © 2015 Magnolia Press

DENG & GE

23. Calyx ≥ 2 mm long; corolla ≥ 3 mm long ........................................................................................................................... 24

- Calyx <2 mm long; corolla <3 mm long ........................................................................................................................... 25

24. Leaf blade 1–3.5 cm long; spike 2.8–7 cm long, ca. 1.5 cm wide .................................................................... P. yatabeanus

- Leaf blade 3.5–7 cm long; spike 0.8–2.5 cm long, less than 1 cm wide................................................................... P. fauriei

25. Leaf blade ca. ≤ 3 cm long; leaf margin entire, slightly revolute; spike ≤ 4 cm long ....................................... P. pentagonus

- Leaf blade usually> 3 cm long; leaf margin serrulate, or rarely entire and revolute; spikes to 7–9 cm long .................... 26

26. Leaf blade obovate-oblong to oblanceolate or linear-lanceolate, margin conspicuously serrate except basal 1/3 entire ....... .............................................................................................................................................................................. P. sampsonii

- Leaf blade linear, margin remote serrate, serrulate or entire ............................................................................................... 27

27. Leaves in whorls of 4–8; calyx ca. 1 mm long; corolla 1.5–1.8 mm long ............................................................ P. stellatus

- Leaves in whorls of 3; calyx ca. 1.6 mm long; corolla ca. 2.5 mm long ........................................................... P. henanensis