Invasive Species Spotlight: Water Hyacinth

 

As you stroll down boardwalks and along shorelines in Hillsborough County, you’ll see some truly beautiful aquatic plants. 

Some send up colorful, delicate flower stalks; some create dense floating mats; some can even grow in wet spots along trails or in puddles. One plant, known throughout the southeastern United States, does all of these things. Meet a land manager’s nemesis and the bane of boaters and fishermen across the world: The common water hyacinth.

 

Originally native to the Amazon river basin, this bright and distinctive flowering plant can now be found on every content except Antarctica. It can grow over a dozen feet a day (yes, feet!) and spreads itself both by cloning and by producing seeds which remain viable for decades. Taking over entire lakes and rivers in only a few months, water hyacinth crowds out other aquatic vegetation, reduces fish populations to near zero, and makes traveling by boat a nightmare. It causes flooding by damming streams and canals and provides the perfect habitat for mosquitoes. The plant has even been blamed for serious economic problems in several countries, where it interferes with fishing operations that many depend on to survive.

In the United States, water hyacinth was first recognized as a problem all the way back in the late 1800s. The government of Louisiana almost voted to import an entire population of hippopotamus just to keep the state’s waterways clear- and what an interesting world we’d be living in now if that bill had passed. Unfortunately, despite efforts to control it, water hyacinth continued spreading and can now be found in warm areas from California and Texas to Georgia and North Carolina. Efforts by the Army Corps of Engineers and others have reduced but not eliminated water hyacinth populations in major waterways. In Florida, the plant is listed as a noxious weed, a prohibited aquatic plant, and a Category I invasive species, and is illegal to buy, sell, or cultivate.

Thick-growing water hyacinth taking over a pond
Nick Lubushko, CC BY-SA 4.0, via Wikimedia Commons

Humans aren’t the only ones affected by this plant’s extreme growth patterns. Water hyacinth grows so aggressively that native plant populations don’t have a chance to compete. The overgrowth of water hyacinth and reduction in other plant species also impacts wildlife species that depend on native plant populations for food. As the plant dies and rots, it can dramatically lower the amount of dissolved oxygen in the surrounding water. This makes it difficult for native fish and amphibians to survive, and the infusion of rotting plant matter can seriously impact the health of Florida’s waterways. Land management organizations across the state (and the country) continue to work to reduce the population of this incredibly invasive plant.

To learn more about water hyacinth, visit the University of Florida Center for Invasive and Aquatic Plants page on water hyacinth. To learn more about invasive plants in Florida, visit their main invasive plant web page.

And be aware- Water hyacinth bears a slight resemblance to one of our favorite native aquatic plants, pickerelweed! Always be certain of a plant’s identity before you decide to remove it. Note the difference between the leaves and flowers of the two plants- pickerelweed grows from the bottom of shallow water and has longer leaves and longer, more slender flower stalks; water hyacinth floats on the surface, can grow in deeper water, and has short fluffy flower stalks and rounder leaves.

Pickerelweed- note longer leaves and flower stalks compared to water hyacinth.