KEY TO THE GENERA based on sterile material

1Leaves usually mucronulate at apex, deciduous in the dry season. Branchlets usually with axillary spines and/or brachyblasts ending in thorns
1'Leaves not mucronulate at apex, persistent. Branchlets usually without, in 1. Olax p.p. sometimes with ramal thorns.
2Climbing shrubs
2'Erect shrubs or trees.
3Leaves subpeltate, 3-5-plinerved. Branches often with spring-like lignescent tendrils
3'Leaves not subpeltate, exclusively pinninerved. Tendrils absent
4Leaves markedly distichous.
4'Leaves indistinctly or not distichous.
5Spines or thorns sometimes present
5'Spines or thorns absent
6Petiole conspicuously thickened distally
6'Petiole hardly or not thickened distally.
7Leaves usually showing scattered blackish points on both faces; nerves slightly impressed above
7'Leaves without such blackish points; nerves not properly impressed above.
8Leaves usually with numerous fine pellucid points visible against strong light
8'Leaves not pellucid-punctate