Key to the genera of the Carolus clade
1. Plants of the Old World; petals white or pink, the posterior petal often proximally yellow in Hiptage.
2. Plants of tropical southeastern Asia; flowers bilaterally symmetrical; sepals leaving petals exposed during enlargement of bud; petals abaxially sericeous; androecium with 1 filament much longer and stouter than the other 9; style 1; fruit breaking apart into 3 samaras, each bearing 3 elongated lateral wings, much longer than wide and much exceeding the nut.
2. Plants of equatorial Africa; flowers radially symmetrical; sepals completely concealing petals during enlargement of bud; petals glabrous; androecium with the 10 filaments ± alike; styles 3; fruit indehiscent, a large woody nut, unwinged or the fertile locule bearing 3 ribs or short winglets (2 lateral and 1 dorsal).
1. Plants of the New World; petals yellow, turning red in age in some species.
3. Shrubs, the stiff branches becoming spinescent at apex in age; fruit bearing clusters of long vascularized setae with bulbous bases.
3. Woody vines, the branches not becoming spinescent; fruit winged or unwinged but without long vascularized setae.
4. Fruit breaking apart into 3 butterfly-shaped samaras, each with 2 dominant lateral wings, the dorsal wing(s) absent or small; sepals not notably accrescent in fruit; anterior style well developed, resembling the 2 posterior styles.
4. Fruit indehiscent, nutlike, unwinged; sepals much enlarged and becoming papery and winglike in fruit; anterior style much smaller than the 2 posterior styles or absent.