Hydrilla (Hydrilla verticillata)

This invasive species is named after Hydra, the nine-headed serpent of Greek mythology.

Listed as a federal noxious weed, Hydrilla, or Hydrilla verticillate, is a submerged, perennial aquatic plant. The plant is named after Hydra because it can grow an entirely new plant from a tiny stem fragment, according to the U.S. Fish & Wildlife Service.

Hydrilla is one of the invasive species monitored by the Brazos River Authority environmental services team.

Invasive species, or plants and animals that are not native to an area, can have a devastating effect on the natural resources of the state. These species can cause economic and ecological damage and impact human health. When non-native species are introduced, they have few natural predators, competitors, or diseases that regulate their populations. These plants and animals can take over ecosystems, spread rapidly, and decrease the biodiversity of native plants and animals.

Hydrilla has small, bright green, pointed leaves with serrated edges. It produces potato‐like tubers at the end of each underground stem that the plant uses for reproduction and food storage, according to the U.S. Fish & Wildlife Service. On the water, the stems branch and grow out horizontally, forming a mat of vegetation.

Native to Asia and possibly mainland Australia, this super invader was first discovered in the U.S. in the 1960s at two separate locations in Florida. Hydrilla can now be found in at least 80 Texas lakes, according to the Texas Parks and Wildlife Department. The plant does so well because it can grow in a wide variety of water conditions, including extremely low light conditions. It has no natural predators or diseases to limit its population and can double its biomass every two weeks during the summer.

Dense mats of Hydrilla can crowd out native aquatic plans, alter water chemistry, cause dramatic swings in dissolved oxygen levels, increase water temperatures and affect the diversity and abundance of fish populations, according to the U.S. Fish & Wildlife Service.

This invasive plant also has the potential to affect power generation and agricultural irrigation by blocking intakes and impeding water flow, according to texasinvasives.org.

Once it infests a water body, it’s difficult and costly to eradicate.

The plant has spread not only through its durability, but also through human interaction. Hydrilla spreads from lake to lake primarily by fragments carried from lake to lake on boats and trailers.

You can help prevent that:

  • Avoid boating through mats of hydrilla.
  • Clean mud or plant fragments from the boat, propeller, boat trailer and all gear, including waders and boots, before leaving a water body.
  • Drain all the water from the boat, including the bilge, live well, motor, and trailer, tackle and gear before leaving the area.
  • Dry the boat trailer and gear after each use.
  • And never release aquarium or water garden plants into the wild. Instead, seal them in a plastic bag and throw them in the trash.

If you find Hydrilla contact the Aquatic Nuisance Species Task Force at 1‐877‐STOP‐ANS.

The most common invasive plants in Texas, in addition to hydrilla, are giant salvinia, water hyacinth, kudzu, alligator weed, Chinese Tallow Tree, and salt cedar.