1Leaf rachis and petiole not winged
1'Leaf rachis and petiole winged
2Petals 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
3Stamens (7 or) 8
3'Stamens 5(-7)
4Leaves hairy
4'Leaves glabrous
5Midrib 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
6Inflorescences ramiflorous, though usually initially in the leaf axils
6'Inflorescences axillary to (rarely) terminal
7Leaflets herbaceous to chartaceous, usually hairy. Sepals up to 7 mm long.
7'Leaflets coriaceous, glabrous. Sepals 7-8 mm long.
8Inflorescences short, up to about 4 cm long, not or hardly branched
8'Inflorescences longer than c. 4 cm, often repeatedly branched
9Twigs slender, 2-7 mm thick. Fruits leathery, inside glabrous. 15. H. ramiflora b. Twigs stout, 8-15 mm thick. Fruits woody, usually hairy inside.
10Fruit wall ± woody
10'Fruit wall leathery
11Petiolules 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
12Leaflets 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
13Fruit 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.
14Leaflets acuminate. Hill and low montane
14'Leaflets obtuse to rounded. Lowland
15Leaflets 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
16Vegetative 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
17Twigs 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
18Inflorescences erect, 1.5-15 cm long
18'Inflorescences pendulous, up to 70 cm long
19Leaflets 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