1A. Involucel apical; leaflets not spinulose-mucronate apically	2
1B. Involucel basal or in the middle; leaflets spinulose-mucronate apically	5
2A. Petiolar gland absent; spines stout, usually fused basally and swollen into enlarged “ant galls”	3. V. erioloba
2B. Petiolar gland present; spines slender, never forming “ant galls”	3
3A. Mature pods dark brown to black, not constricted between the seeds	4
3B. Mature pods light brown, strongly constricted between the seeds	2. V. constricta
4A. Midvein and lateral veins obvious and slightly raised; pods subterete to terete, obliquely to longitudinally finely striate	4. V. farnesiana var. farnesiana
4B. Midvein and lateral veins not obvious; pods oblong-elongate or subglobose, usually not striate	1. V. caven
5A. Some spines fused basally into inflated ± bilobed “ant galls” or the spines fusiform inflated	6
5B. Spines not inflated into ± bilobed “ant galls” or fusiform inflated	7. V. xanthophloea
6A. “Ant galls” composed of pairs of spines fused below into an inflated ± bilobed structure	6. V. seyal var. fistula
6B. “Ant galls” composed of pairs of spines, each spine fusiform-inflated but not fused with the other member of the pair except basally and free for almost its entire length	5. V. karroo