Key to species of Kaempferia in Cambodia and Lao PDR

1. Flowers appearing before leaves (subgenus Protanthium) ............................................................... 2

– Flowers and leaves appearing at the same time (subgenus Kaempferia) ......................................... 3

2. Leaves 2–4; blade oblong, green or purple, pubescent; petiole 10–20 mm long ......... K. rotunda L.

– Leaves 5–7; blade elliptic, upper surface glabrous, lower pubescent; petiole absent ........................ .................................................................................... K. xiengkhouangensis Picheans. & Phokham

3. Ligule present,> 2 mm long and clearly visible; flowers flat, directed upward ............................... 4

– Ligules very small, ± 2 mm long or absent; flowers cup-shaped, directed upward or sideward, or flat, directed upward ................................................................................................................................ 8

4. Leaves erect, blade oblong ..................................................... K. sawanensis Picheans. & Koonterm

– Leaves flat on the ground, blade oblong or ovate to orbicular ......................................................... 5

5. Lateral staminodes and labellum pink to purple; anther crest pink, apex non bifid ........................... ............................................................................................................ K. marginata Carey ex Roscoe

– Lateral staminodes white; labellum white with violet patch; anther crest white, apex bifid ............ 6

6. Anther crest rectangular, bifid, divided by 1 mm, apex rounded-emarginate ....... K. laotica Gagnep.

– Anther crest elliptic or cuneate-flabellate, bifid, divided to the base ................................................ 7

7. Anther crest elliptic, 4× 4 mm, lobes rounded .............................................................. K. galanga L.

– Anther crest cuneate-flabellate, 6 × 7 mm, lobes emarginate-acute ........... K. harmandiana Gagnep.

8. Nyctanthous (night-flowering) .......................................................................................................... 9

– Hemeranthous (day-flowering) ....................................................................................................... 10

9. Ligule present, <1 mm long; blade ensiform, coriaceous; lateral staminodes spathulate; stamen sessile ........................................................................................................................ K. fissa Gagnep.

– Ligule absent; blade subulate, soft; lateral staminodes obovate; stamen attached at mouth of floral tube, filament 2 mm long .................................................................................... K. filifolia K.Larsen

10. Bracteoles two per flower, fused at base, outside of floral tube puberulous ....................................... ............................................................................................. K. gigantiphylla Picheans. & Koonterm

– Bracteoles two per flower, opposite, outside of floral tube glabrous ...............................................11

11. Ovary puberulous ................................................................................... K. parviflora Wall. ex Baker

– Ovary glabrous ................................................................................................................................ 12

12. Leaf one, blade flat on the ground, orbicular .................................................. K. siamensis Sirirugsa

– Leaf one to three, blade flat on the ground to erect, oblong to ovate ............................................. 13

13. Floral tube ± 55 mm long; lateral staminodes obovate ................................................................... 14

– Floral tube Ẑ 55 mm long; lateral staminodes oblong or obovate or spatulate ............................... 15

14. Rhizome short, vertical; lateral staminode and labellum pink, anther crest entire or slightly crenate with pink patch ................................................................................................... K. larsenii Sirirugsa

– Rhizome short horizontal and very slender; lateral staminodes and labellum pure white; anther crest bifid and pure white ....................................................... K. champasakensis Picheans. & Koonterm

15. Floral orientation sideward; floral tube> 90 mm long; staminodes oblong, 40 × 12 mm; anther crest obovate, 10 × 6 mm; ovary 8× 3.5 mm diameter ..................................... K. nemoralis Insis. sp. nov.

– Floral orientation upward; floral tube ± 90 mm long; staminodes oblong or spatulate; anther crest flabellate or narrowly ovate to ovate; ovary 5× 0.5–3 mm diameter .............................................. 16

16. Floral tube 75-90 mm long; staminodes oblong, 30 × 10 mm; anther crest flabellate, 3 × 5 mm to 12 × 6 mm, white; ovary 5 × 3 mm diameter ......................................... K. pascuorum Insis. sp. nov.

– Floral tube 55-62 mm long; staminodes spatulate, 20 × 12–16 mm; anther crest narrowly ovate to ovate, 4–6× 3 mm; ovary 5 × 0.5 mm diameter ..................... K. attapeuensis Picheans. & Koonterm