- any of certain aquatic plants belonging to the genus Nymphoides, of the gentian family, especially N. aquatica, having floating, more or less heart-shaped leaves and a cluster of small, white, five-petaled flowers.
- a related plant, Nymphoides cordata, of North America, having a cluster of white flowers and round or somewhat oval leaves that are purple beneath.
- any perennial aquatic freshwater plant of the genus Nymphoides, esp N. lacunosum, having floating heart-shaped leaves: family Menyanthaceae