KEY TO THE GENERA

1Capsule loculicidally dehiscent with 4 valves; axis persistent. Seeds comose. Floral tube present. Petals 4, white, pinkish or red. Stamens 8. Stem-base without aerenchyma
1'Capsule irregularly dehiscent; axis not persistent. Seed not comose. Floral tube absent. Petals yellow, if white or creamy then flowers 5-merous and floating aquatic plant adorned with short spongy aeren-chyma-roots at the nodes. Stamens 4-10. Stem-base not rarely covered by aerenchyma.