Pontederia crassipes

Water hyacinth

Nonnative to FloridaFlorida Prohibited Aquatic Plants ListFISC Category 1

Origin: Amazon basin1
Introduction to Florida: 1884 (ornamental, agriculture)2

The water hyacinth is a floating plant. This invasive nuisance is planta non grata in much of the world where it often jams rivers and lakes with uncounted thousands of tons of floating plant matter. A healthy acre of water hyacinths can weigh up to 200 tons! In the U.S., water hyacinth is present throughout the southeast, as well as in California and Washington state. In Florida, where for 100 years this weed had the upper-hand in water management, the water hyacinth in most places is under “maintenance control”: field crews constantly working to keep the plant numbers at their lowest possible levels, in exchange for the rivers and lakes remaining usable.


Eichhornia crassipes grows in all types of freshwaters. They vary in size from a few inches to over three feet tall. They have showy lavender flowers. Their leaves are rounded and leathery, attached to spongy and sometimes inflated stalks. The plant has dark feathery roots. Water hyacinth may be confused with frog’s-bit, Limnobium spongia.

  • Eichhornia crassipes mats clog waterways, making boating, fishing and almost all other water activities, impossible
  • water flow through water hyacinth mats is greatly diminshed
  • an acre of water hyacinth can weigh more than 200 tons; infestations can be many, many acres in size; mats may double their size in as little as 6-18 days (Mitchell 1976);
  • water hyacinth mats degrade water quality by blocking the air-water interface and greatly reducing oxygen levels in the water, eliminating underwater animals such as fish (Penfound & Earle 1948)
  • water hyacinth greatly reduces biological diversity: mats eliminate native submersed plants by blocking sunlight, alter emersed plant communities by pushing away and crushing them, and also alter animal communities by blocking access to the water and/or eliminating plants the animals depend on for shelter and nesting (Gowanloch 1944)
  • in Florida, millions of dollars a year used to be spent on water hyacinth control; finally getting the plant under “maintenance control” has greatly reduced that expenditure