Pontederia is a genus of tristylous aquatic plants, members of which are commonly known as pickerel weeds. Pontederia is endemic to the Americas, distributed from Canada to Argentina, where it is found in shallow water or on mud. The genus was named by Linnaeus in honour of the Italian botanist Giulio Pontedera. Pontederia cordata, and another member of the family, Eichhornia crassipes, have become invasive in many tropical and temperate parts of the globe, but are, on the other hand, efficient biological filters of polluted water in constructed wetlands.