KEY TO THE GENERA based on flowering material

1Leaves 3-5-plinerved, at base subpeltate. Climbing shrub; axillary tendrils often present
1'Leaves penninerved (if ± 3-plinerved a tree), never peltate. Tendrils absent.
2Stamens and staminodes present
2'Stamens present; staminodes absent.
3Stamens fully fused into a tube. Flowers unisexual, plant monoecious
3'Stamens not fused (sometimes partly adnate to the petals). Flowers generally bisexual.
4Stamens 8 or 10, half of them epipetalous, the other half episepalous. Leaves usually mucronulate at apex. Spines and/or thorns generally present
4'Stamens all epipetalous. Leaves not mucronulate at apex. Spines and/or thorns absent.
5Flowers interruptedly arranged in elongate spikes
5'Flowers arranged in short racemes, panicles, or mostly in fascicles.
6Stamens 8 or 10, arranged in pairs before each petal
6'Stamens 4-7, solitary before each petal.
7Petals entirely free
7'Petals fused in the lower half.
8Calyx cupular, ± truncate to very shortly 6-dentate. Petals thick-fleshy. Anthers apically penicillate
8'Calyx indistinct, merely a rim with minute teeth. Flower supported by an epicalyx consisting of 3 concrescent bracts. Petals thin. Anthers not penicillate at apex