Hydrilla (Hydrilla Verticila) is a submerged aquatic plant that roots in the bed of a waterbody. It is native to Africa, Australia, and parts of Asia. It is considered the most problematic aquatic plant in the US. there are two varieties of hydrilla in the US; one produces only female flowers making it dioecious, while the other is monoecious and produces both male and female flowers. The plants in New York are monoecious and produce both female and male flowers. It is believed that hydrilla was introduced in the US via the aquarium trade. Hydrilla is a federally listed noxious weed, listed as a Class A weed on Washington’s Noxious Weed List, and is on the Washington State Department of Agriculture’s Quarantine list


Hydrilla invades deep, dark waters where most native plants can’t grow; it is more efficient at taking up nutrients than native species and has the ability to produce turions and tubers which can easily generate new plants–these characteristic give hydrilla a competitive edge against native aquatic vegetation.  Furthermore, hydrilla populations block out sunlight and suppress native vegetation. Major hydrilla colonies can alter the physical and chemical characteristics of lakes and deter recreational activities and reduce lakeshore property values.


Hydrilla is found in freshwater bodies and is well established throughout southern portions of the US.

Identifying Hydrilla and Look-Alikes


Prevention: Hydrilla can easily sprout new plants from root and stem fragments and is easily spread by boat propellers and other aquatic recreational equipment. Therefore, to prevent its’ spread it is important for boaters to Clean, Drain, Dry their boats and equipment before leaving/entering a body of water.

Physical control: Hydrilla can be controlled physically by hand removal via snorkelers and divers. It is important to remove tubers from plants to be successful with this control method.

Chemical control: Aquatic herbicides can be used but type and regulations depend on the state. Contact the local DEC office for information.

Photo Credits:

Top photo collage in clockwise order: Chris Evans, River to River CWMA Bugwood.org; Michael Frank Galileo Group Inc. Bugwood.org; Robert Videki, Doronicum Kft. Bugwood.org.  Hydrilla vs look-alikes photos in clockwise order: Tim Krynak  Cleveland Metroparks, Bugwood.org; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org;Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org. Native look-alikes of Hydrilla and Brazilain Waterweed compliments of Lake George Association


Great Lakes Hydrilla Collaborative

Hydrilla Fact Sheet

Aquatic Invasive Species: Hydrilla

General Information About Hydrilla: Non-native Invasive Freshwater Plants. 

Hydrilla: Noxious Weed Control Board (NWCB)


Prevent the introduction of invasive species into the SLELO PRISM.

Rapidly detect new and recent invaders and eliminate all individuals within a specific area.

Share resources, including funding personnel, equipment, information, and expertise.

Collect, utilize, and share information regarding surveys, infestations, control methods, monitoring, and research.

Control invasive species infestations by using best management practices, methods and techniques to include: ERADICATION (which is to eliminate all individuals and the seed bank from an area), CONTAINMENT (which is reducing the spread of established infestations from entering an uninfested area) and SUPPRESSION which is to reduce the density but not necessarily the total infested area.

Develop and implement effective restoration methods for areas that have been degraded by invasive species and where suppression or control has taken place.

Increase public awareness and understanding of invasive species.

Develop and implement innovative technologies that help us to better understand, visualize, alleviate or manage invasive species and their impacts or that serve to strengthen ecosystem function and/or processes.

Rob Williams                              rwilliams@tnc.org                     Program Director

Megan Pistolese megan.pistolese@tnc.org
Outreach and Education

Brittney Rogers brittney.rogers@tnc.org 
Aquatic Invasive Species

Robert Smith       robert.l.smith@tnc.org 
Terrestrial Invasive Species

Zachary Simek    zachary.simek@TNC.ORG     Conservation and GIS Analyst

During this time the best way to contact our team is via email.