1Inflorescence usually a median triad or pentad developing from the apical bud of the shoot (Bismarck Archipelago & Karkar Island, Papua New Guinea); section Leiospermum
1'Inflorescence composed of 1-3 pairs of dyads or tetrads inserted in the opposite axils of the most distal pair of leaves and sometimes in axils of subdistal leaves; apical bud of shoot, between central peduncles of the partial inflorescences, present and usually dormant, rarely developing vegetatively during reproduction (throughout Malesia); section Fasciculatae
2Flowers inserted on the inflorescence axes singly, each individual pedicel subtended by a bract; leaves simple
2'Flowers inserted on the inflorescence axes in fascicles, each fascicle subtended by a bract; leaves usually imparipinnate, less often simple or trifoliolate
3Leaves simple or trifoliolate, the blades 4-9.5 by 1.7-4.4 cm, glabrous (Philippines, Sulawesi)
3'Leaves imparipinnate, lateral leaflets in 1-19 pairs, only occasional leaves trifoliolate or if regularly trifoliolate, then leaflets smaller and densely hirsute (W. cf. pullei, New Guinea)
4Leaflets small, the largest laterals 0.6-3.2 by 0.2-1.5 cm, often in numerous pairs (2-19)
4'Leaflets medium-sized, the largest laterals 2.4-10 by 0.6-3.7 cm, usually in fewer pairs (1-8)
5Leaflets bullate and carinate, the margins strongly recurved and revolute (Mt Kinabalu)
5'Leaflets flat or if slightly bullate then the margins not rolled back
6Petiole and rachis segments narrowly winged and leaflets numerous, 3-20 pairs; stems and leaflets glabrous
6'Petiole and rachis segments terete or semiterete, or if narrowly winged then leaflets fewer, 1-6 pairs; young stems and young leaflets tomentose, velutinous or sericeous, sometimes glabrescent
7Leaflets inserted at almost 90° to rachis, and secondary veins at almost 90° to midrib.
7'Leaflets inserted at an acute acroscopic angle and secondary veins at an acute acro-scopic angle to midrib
8Lateral leaflets obovate or oblanceolate (New Guinea)
8'Lateral leaflets oblong to narrowly ovate (Peninsular Malaysia)
9Indumentum on young twigs pilose and on leaves pilose and pubescent
9'Indumentum on young twigs and leaves absent or pubescent to villous-tomentose, not pilose
10Terminal leaflet markedly rhomboidal and distinctly larger than the largest laterals.
10'Terminal leaflet narrowly elliptic, only slightly larger than the largest laterals
11Lateral leaflets usually in 5-7 pairs, the largest 2-6.5 by 0.6-1.4 cm, decreasing in size proximally along the rachis; margin of stipules often wavy or coarsely toothed (Philippines)
11'Lateral leaflets in 3-6 pairs, the largest 3-5 by 1-1.6 cm, not markedly decreasing in size proximally; margin of stipules entire (N Sulawesi)
12Leaflets drying grey or dark chestnut above and chestnut beneath, lateral ones in 1-4 pairs, the largest 2.4-7 by 0.6-1.9 cm; petiole and rachis sometimes narrow- ly winged
12'Leaflets drying dark green or brown but not chestnut, lateral ones in 1-8 pairs, the largest 4.2-10 by 1.4-3.5 cm; petiole and rachis not winged
13Underside of leaflets bearing short scurfy hairs; indumentum on growing tips, stipules, leaf rachises and inflorescence axes dense rusty or golden brown villous-tomentose; lateral leaflets elliptic to obovate, the base ± symmetrical and the apex rounded or obtuse
13'Underside of leaflets glabrous; indumentum on growing tips, stipules, leaf rachises and inflorescence axes puberulent to tomentose or absent, not rusty or golden brown; lateral leaflets lanceolate to elliptic or ovate, the base usually asymmetrical and the apex usually acute or acuminate
14Lateral leaflets lanceolate, narrowly elliptic to ovate, in 1-8 pairs
14'Lateral leaflets narrowly to broadly elliptic, not broader towards to base, in 2-3 pairs
15Pedicels 1.5-3 mm long (widespread in Malesia except Sulawesi and the Philippines)
15'Pedicels very short, 0.2-0.5 mm (Sulawesi)
16Lateral leaflets attenuate into a petiolule at base, often conduplicate, 5-8.5 by 2-3.7 cm
16'Lateral leaflets acute at base, ± sessile, not conduplicate, 4.8-6.4 by 1.4-2.1 cm.