| 1 | Leaf blade puberulent beneath |
| 1' | Leaf blade glabrous beneath |
| 2 | Inflorescence terminal and branched, 9.5-12 cm long; corolla densely pubescent all over outside except at very base |
| 2' | Inflorescence in axillary cymes, rarely terminal, 1-5.6 cm long; corolla glabrous or sparsely pubescent only in lower half outside |
| 3 | Leaves glabrous above; inflorescence 3-5.6 cm long; corolla sparsely pubescent in lower half outside |
| 3' | Leaves sparsely pubescent above; inflorescence c. 1 cm long; corolla glabrous outside |
| 4 | Corolla tube sparsely puberulent, at least in part, outside |
| 4' | Corolla tube glabrous outside |
| 5 | Branchlets densely pubescent when young, sometimes glabrescent when older; corolla tube sparsely pubescent only in lower half outside |
| 5' | Branchlets glabrous, even when young; corolla tube sparsely and minutely papillate-pubescent all over or pubescent only in upper half |
| 6 | Inflorescence mostly longer than subtending leaves; secondary veins on leaves weakly to not visible beneath |
| 6' | Inflorescence shorter than subtending leaves; secondary veins on leaves strongly prominent beneath |
| 7 | Branchlets minutely puberulent (use a lens!) |
| 7' | Branchlets glabrous |
| 8 | Pedicels without numerous bracteoles; corolla tube 6.8-8.2 mm long |
| 8' | Pedicels with numerous bracetoles; corolla tube 4.2-6 mm long |
| 9 | Inflorescence densely congested in leaf axils, shorter than subtending petiole |
| 9' | Inflorescence not densely congested, mostly longer than subtending petioles |
| 10 | Corolla tube < 6 mm long |
| 10' | Corolla tube ≥ 6 mm long |
| 11 | Pedicels with numerous bracteoles |
| 11' | Pedicels with 2 or fewer bracteoles |
| 12 | Leaves mostly with rounded or retuse apices; ultimate inflorescence nodes strongly congested so as to appear umbelliform; fruit globose |
| 12' | Leaves mostly acute to acuminate, more rarely to rounded; ultimate inflorescence branches not umbelliform; fruit various but not globose |
| 13 | Leaf blade coriaceous, base decurrent onto petiole; stamens inserted at 0.6-0.7 of length of tube from base; fruit long and torulose, constrictions between bulges around seeds mostly not less than half as wide as bulges around seeds |
| 13' | Leaf blade variable but mostly not coriaceous, base rounded to cuneate; stamens inserted at 0.3-0.6 of length of tube from base; fruit ellipsoid, fusiform or strongly moniliform with constrictions between bulges around seeds less than half as wide as bulges around seeds |
| 14 | Corolla tube 2.7-4 mm long; fruit ellipsoid or fusiform. — Probably not in Borneo |
| 14' | Corolla tube 4-4.7 mm long; fruit strongly moniliform. — Borneo |
| 15 | Pedicels with many bracteoles; stamens inserted at around 0.5 of tube length from base |
| 15' | Pedicels with 2 bracteoles or fewer; stamens inserted at 0.2-0.4 of tube length from base |
| 16 | Inflorescence almost always longer than subtending leaves; secondary veins on leaves weakly to not visible beneath |
| 16' | Inflorescence only very rarely longer than subtending leaves; secondary veins on leaves prominent beneath |
