Pontederia Genus

Pontederia is a genus of aquatic flowering plants in the family Pontederiaceae, within the order Commelinales. Commonly known as pickerel weeds, its members grow in shallow water or on mud, and are characterised by large waxy leaves, succulent stems, and a dense pad of fibrous roots. The roots give rise to rhizomes that allow rapid colonisation by vegetative reproduction, making these plants effective colonisers of freshwater margins. Species are perennial and produce tall, striking spikes of flowers in summer.

The genus is endemic to the Americas, with a natural distribution stretching from Canada south to Argentina. It was named by the Swedish botanist Carl Linnaeus in honour of Giulio Pontedera, an eighteenth-century Italian botanist. The family Pontederiaceae has historically included the genus Eichhornia, but recent taxonomic revisions by Pellegrini and Horn (reflected in Plants of the World Online as of January 2024) have absorbed several former Eichhornia species into Pontederia — most notably water hyacinth, now recognised as Pontederia crassipes.

Pontederia exhibits a tristylous floral arrangement, a relatively rare breeding system in which flowers occur in three distinct style-length morphs, promoting cross-pollination. The bee Dufourea novaeangliae is a specialist pollinator that exclusively visits Pontederia cordata, while waterfowl consume the plant's fruit, contributing to seed dispersal. Two species — Pontederia cordata (pickerelweed) and Pontederia crassipes (water hyacinth) — have become invasive in many tropical and temperate regions outside the Americas, yet are also exploited as efficient biological filters of polluted water in constructed wetland systems.