| 1 | Leaf rachis and petiole not winged |
| 1' | Leaf rachis and petiole winged |
| 2 | Petals not clawed, without auricles, thin-fleshy. Arillode completely or nearly completely enveloping the seed |
| 2' | Petals clawed and auricled, membranous. Arillode restricted to a ring around the hilum |
| 3 | Stamens (7 or) 8 |
| 3' | Stamens 5(-7) |
| 4 | Leaves hairy |
| 4' | Leaves glabrous |
| 5 | Midrib above (in dried leaves) sunken, nerves flat to sunken. Fruit lobes erect, completely united over 3.5 cm |
| 5' | Midrib and nerves above (in dried leaves) slightly raised. Fruit lobes widely spreading, partly united over 4-7 mm |
| 6 | Inflorescences ramiflorous, though usually initially in the leaf axils |
| 6' | Inflorescences axillary to (rarely) terminal |
| 7 | Leaflets herbaceous to chartaceous, usually hairy. Sepals up to 7 mm long. |
| 7' | Leaflets coriaceous, glabrous. Sepals 7-8 mm long. |
| 8 | Inflorescences short, up to about 4 cm long, not or hardly branched |
| 8' | Inflorescences longer than c. 4 cm, often repeatedly branched |
| 9 | Twigs slender, 2-7 mm thick. Fruits leathery, inside glabrous. 15. H. ramiflora b. Twigs stout, 8-15 mm thick. Fruits woody, usually hairy inside. |
| 10 | Fruit wall ± woody |
| 10' | Fruit wall leathery |
| 11 | Petiolules 5 or more mm long. Inflorescences initially in foliate axils, up to 22 cm long |
| 11' | Petiolules 0-4 mm long. Inflorescences exclusively ramiflorous/cauliflorous, up to 50 cm long |
| 12 | Leaflets abruptly acuminate. Axillary inflorescences solitary. Fruits 2.2-2.5 cm wide and about as high, hardly stipitate |
| 12' | Leaflets gradually acuminate. Axillary inflorescences clustered like the rami- and/ or cauliflorous ones. Fruits 2.5-3.4 cm wide, c. 1.5 times as wide as high, distinctly stipitate |
| 13 | Fruit lobes spreading, usually united for less than 1 cm |
| 13' | Fruit lobes erect, united for more than 1 cm, hence the fruit ovoid to obovoid. |
| 14 | Leaflets acuminate. Hill and low montane |
| 14' | Leaflets obtuse to rounded. Lowland |
| 15 | Leaflets glabrous to sparsely hairy on midrib and nerves on both sides 3. H. carrii b. Leaflets on midrib and nerves densely puberulous on both sides, beneath also sparsely so on veins and veinlets |
| 16 | Vegetative parts, at least when young, distinctly and ± densely hairy |
| 16' | Twigs glabrous except for the terminal bud, leaves glabrous or at most very sparsely hairy on axes, midrib, and nerves |
| 17 | Twigs rather slender, 3-10 mm thick. Leaves up to 5-jugate. Leaflets distinctly petiolulate, nerves above ± raised |
| 17' | Twigs rather stout, 9-15 mm thick. Leaves 5-9-jugate. Leaflets subsessile, the nerves slightly sunken above |
| 18 | Inflorescences erect, 1.5-15 cm long |
| 18' | Inflorescences pendulous, up to 70 cm long |
| 19 | Leaflets at most thin-puberulous on midrib and nerves on both sides |
| 19' | Leaflets hirsute on both sides, most densely so on he midrib and on the nerves on the upper side |
