Alternanthera philoxeroides

Other Common Names

None for this invasive

Plant Category

Aquatic, Perennial

Invasive Description

Native to South America, Alligatorweed was introduced to the United States around 1900. It is an emergent or rooted floating perennial plant that often forms mats on top of waterways. The white flowers occur in short, headlike spikes. The flowers resemble those of white clover.

Ecological Threat

Alligatorweed forms thick mats that crowd out native aquatic vegetation, reduces light for aquatic plants and animals, retards water flow, lowers dissolved oxygen levels and increases sedimentation. Flooding may result from impeded drainage. The mats can restrict water flow for irrigation, clog pumps and discourage boating, swimming, fishing and other water recreation.

Alligatorweed is on the Texas Dept. of Agriculture’s List of Noxious Plants and on Texas Parks and Wildlife’s list of Invasive, Prohibited and Exotic species which are illegal to sell, distribute or import into Texas.

You may not want or need to replace this invasive plant. One possibility is shown.

How to Eradicate

For information on how to eradicate this invasive, view our statement on herbicide use and preferred alternatives for invasive plants.

Native Alternatives

You can replace this invasive plant with native alternatives. Here are some plants that make superior replacements.

Match your location on the Texas map to the color squares on the replacement plants below to find suitable replacements for your ecoregion.

Click for more details about the ecoregions