Key to Meistera species in Cambodia, Laos and Vietnam.

1. Flower open; labellum white and yellow, with some red markings; fruit smooth .............................................................................2

- Flower gullet-type or open; labellum white and yellow or yellow, with or without some red markings or tinge; fruit echinate......3

2. Fruit ellipsoid, shiny, lenticellate, glabrous....................................................................................................................... M. koenigii

- Fruit globose to sub-globose, matt, puberulent ................................................................................................................... M. tomrey

3(1). Labellum yellow or yellow red...........................................................................................................................................................4

- Labellum white and yellow, with or without some red or markings or tinge.....................................................................................7

4. Labellum plain yellow, or rarely with two thin red lines; anther with minute crest.............................................................. M. sudae

- Labellum with prominent red markings; anther with prominent crest ...............................................................................................5

5. Flower open; labellum prominently clawed ............................................................................................................... M. cristatissima

- Flower gullet-type; labellum not clawed............................................................................................................................................6

6. Leaf blade abaxially pubescent; ligule villous; calyx lemon-yellow ............................................................................. M. verrucosa

- Leaf blade abaxially glabrous; ligule glabrous with only ciliate margin; calyx pink to scarlet.................................... M. vespertilio

7(3). Peduncle at least 150 cm long ................................................................................................................................................ M. celsa

- Peduncle less than 40 cm long............................................................................................................................................................8

8. Leaf sheath prominently reticulate to muriform.................................................................................................................................9

- Leaf sheath smooth, striate to finely reticulate.................................................................................................................................10

9. Leaf blade abaxially pubescent; ligule brown, red or green, densely pubescent with brown hair; anther crest semi-circular to bluntly squared to oblong .............................................................................................................................................. M. muriformis

- Leaf blade abaxially glabrous; ligule bright to dark red, glabrous; anther crest trilobed................................................ M. chinensis

10(8). Infructescence including peduncle 25–35 cm long ..........................................................................................................................11

- Infructescence including peduncle not more than 20 cm long.........................................................................................................12

11. Inflorescence globose, with gelatinous mucilage; fruit with straight spines............................................................ M. elephantorum

- Inflorescence cylindrical, without gelatinous mucilage; fruit with curved or hooked spines ..................................... M. gagnepainii

12(10). Ligule glabrous; fruit green or red ...................................................................................................................................................13

- Ligule tomentose; fruit red ...............................................................................................................................................................14

13. Leaf blade abaxially with hairy primary veins, with caudate apex to 2 cm; fruit green ............................................ M. echinocarpa

- Leaf blade glabrous on both sides, with caudate apex to 4 cm; fruit red .......................................................................... M. caudata

14(12). Labellum bifid; fruit with branched spines ............................................................................................................. M. stephanocolea

- Labellum trilobed; fruit with simple spines..................................................................................................................... M. calcarata