1a. Leaf with petiole expanded and flattened, the leaf resembling that of many Citrus...2

1b.Leaf with petiole slender, canaliculate. . . . . . . . 11

2a. Stipe of spadix sharply bent at anthesis, fertile portion of spadix held adjacent to peduncle. . . . . . . . . . . 9. P. scandens

2b.Stipe of spadix ± straight at anthesis . . . . . . . 3

3a. Fertile portion of spadix long slender-cylindrical, often slightly tortuose; leaves of flowering shoots with petiole at least eight times longer than lamina. . . . 8. P. repens

3b.Fertile portion of spadix globose, obtuse-ellipsoid or stout cylindrical, if stout cylindrical then straight and leaves of flowering shoots with petiole shorter than lamina . . 4

4a. Spadix stout cylindrical; central Vietnam . . . . . . 2. P. dzui

4b.Spadix globose to obtuse-ellipsoid; various localities . . . . . 5

5a. Stipe of spadix short (no more than twice as long as fertile portion of spadix) . . 6

5b.Stipe of spadix long (more then three times as long as fertile portion of spadix) . 7

6a. Flowering shoots arising at many leaf axils along long pendent fertile shoots, inflorescences
thus often very numerous; spathe purple, fertile portion of spadix cream 9. P. scandens

6b.Flowering shoots arising at only the distal-most leaf axils of short spreading fertile shoots, inflorescences thus rather few; spathe green, fertile portion of spadix white to yellow. . . . . . . . . . . 1. P. chinensis

7a. Fertile portion of spadix very small (5 mm diam. or less at anthesis) . . . 8

7b.Fertile portion of spadix moderate to large (10 mm diam. or more at anthesis) . . 9

8a. Peduncle 25 – 40 x 0.5 – 1 mm, slender; stipe10 – 18 x 0.23 – 0.75 mm, very slender. . . . . . . . . . . 5. P. kerrii

8b.Peduncle 0 – 3 (– 5) x c. 1 mm, stout; stipe 10 – 12 x 1 – 1.25 mm, stout . 7. P. pilulifer

9a. Spathe white, fertile portion of spadix yellow; peninsular Thailand, central & southern
Vietnam, ?Cambodia . . . . . . . . . 10

9b.Spathe green, fertile portion of spadix purple; north Vietnam, ?China. . . 4. P. grandis

10a. Petiole twice or more the length of lamina, bright to mid-green, congested-distichous; juvenile stage with weakly angled to subterete stems, leaves bright green, spreading to loosely appressed to substrate; peninsular Thailand . . . . . 6. P. macrocephalus

10b.Petiole half or less the length of lamina, grey-green, spaced out; juvenile stage with compressed, winged, rectangular stems, leaves blue- to grey-green, tightly appressed tosubstrate; central & southern Vietnam, ?Cambodia . . . 3. P. gigantipes

11a. Spadix with flowers densely clustered, the whole appearing uniformly cylindrical . 12

11b.Spadix with flowers scattered along a slender axis . . . . 10. P. curtisii

12b.Spathe never as above; inflorescence variously orientated . . . . 13

13a. Spathe lorate, mid-green; spadix stipitate; peduncle less than 60 mm long 13. P. lorispathus

13b.Spathe lanceolate to triangular, variously coloured; spadix sessile or stipitate, if stipitate then peduncle more than 100 mm long . . . . . . . 14

14a. Peduncle 15 – 50 mm; spathe lanceolate, 25 – 100 x 10 – 40 mm; spadix sessile. . . . . . . . . . 12. P. lancifolius

14b.Peduncle 100 – 190 mm; spathe triangular, 60 – 90 x 15 – 20 mm; spadix stipitate. . . . . . . . . . 14. P. touranensis