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You are here: Home / Aquatic Species / Species Profiles / Hydrilla
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HydrillaScientific name: Hydrilla verticillata (L. f.) Royle (ITIS)

Common names: Hydrilla, Florida elodea, water thyme, Indian star-vine

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Selected Resources

Native To: Eastern Hemisphere; U.S. strains possibly originated in Asia (Balciunas et al. 2002)

Date of U.S. Introduction: 1950s (Masterson 2007)

Means of Introduction: Aquarium trade (Masterson 2007)

Impact: Crowds out native species; impedes irrigation and boating (Balciunas et al. 2002)

Current U.S. Distribution:

Federally Regulated:

  • Noxious Weeds Program
    USDA. APHIS. Plant Protection and Quarantine.
    Includes species listed as a Federal Noxious Weed under the Plant Protection Act, which makes it illegal in the U.S. to import or transport between States without a permit.



Selected Resources:

Council or Task Force

Species of Concern Fact Sheet: Hydrilla
Aquatic Nuisance Species Task Force.

Invasive Plants of California's Wildlands - Hydrilla verticillata
California Invasive Plant Council.
In online book: Bossard, C.C., J.M. Randall, and M.C. Hoshovsky (Editors). 2000. Invasive Plants of California's Wildlands. University of California Press. Berkeley, CA

Southeast Exotic Pest Plant Council Invasive Plant Manual - Hydrilla
Southeast Exotic Pest Plant Council.

Priority Species: Hydrilla
Washington State Recreation and Conservation Office. Washington Invasive Species Council.

Fact Sheet: Hydrilla (Apr 2016; PDF | 496 KB)
Alberta Invasive Species Council (Canada).
See also: Fact Sheets for more information about individual invasive species, including those listed as "Prohibited Noxious" and "Noxious" under the Alberta Weed Control Act


Federal Noxious Weed Disseminules of the U.S. - Fact Sheet: Hydrilla verticillata
USDA. APHIS. PPQ. Center for Plant Health Science and Technology; California Department of Food and Agriculture.

Pacific Island Ecosystems at Risk (PIER) - Hydrilla verticillata
USDA. FS. Institute of Pacific Islands Forestry.

Alaska Exotic Plants Information Clearinghouse (AKEPIC): Species Biography - Hydrilla (Feb 7, 2011; PDF | 113 KB)
University of Alaska - Anchorage. Alaska Center for Conservation Science.
See also: Non-Native Plant Species List for additional factsheets (species biographies) and species risk assessment reports of non-native species present in Alaska and also non-native species currently not recorded in Alaska (potential invasives).

Invasive Plant Atlas of New England (IPANE) - Hydrilla
University of Georgia. Center for Invasive Species and Ecosystem Health.

Invasive Plant Atlas of the MidSouth - Hydrilla
Mississippi State University. Geosystems Research Institute.

Invasive Plant Atlas of the United States - Hydrilla
University of Georgia. Center for Invasive Species and Ecosystem Health.

Fact Sheet: Hydrilla
Massachusetts Introduced Pests Outreach Project.

New York Invasive Species Information - Hydrilla
New York Invasive Species Clearinghouse.

NEANS Panel Online Guide - Hydrilla
Northeast Aquatic Nuisance Species Panel.

Texas Invasives Database - Hydrilla verticillata

The Quiet Invasion: A Guide to Invasive Species of the Galveston Bay Area - Hydrilla, Waterthyme, Florida Elodea
Texas Commission on Environmental Quality, Galveston Bay Estuary Program; Houston Advanced Research Center (HARC).

Invasive Species Compendium - Hydrilla verticillata
CAB International.

Plantwise Technical Factsheet - Hydrilla (Hydrilla verticillata)
CABI. Plantwise Knowledge Bank.

Global Invasive Species Database - Hydrilla verticillata (aquatic plant)
IUCN. Species Survival Commission. Invasive Species Specialist Group.

Invaders Factsheet: Hydrilla
Ontario's Invading Species Awareness Program (Canada).

Federal Government

U.S. National Plant Germplasm System - Hydrilla verticillata
USDA. ARS. National Genetic Resources Program. GRIN-Global.

PLANTS Database - Hydrilla
USDA. NRCS. National Plant Data Center.

Nonindigenous Aquatic Species Database: Fact Sheet - Hydrilla
DOI. USGS. Wetland and Aquatic Research Center.
Provides distribution maps and collection information (State and County).

Indian River Lagoon Species Inventory - Hydrilla verticillata
Smithsonian Institution. Smithsonian Marine Station at Fort Pierce.

National Exotic Marine and Estuarine Species Information System (NEMESIS): Chesapeake Bay Introduced Species Database - Hydrilla verticillata
Smithsonian Institution. Smithsonian Environmental Research Center. Marine Invasions Research Lab.

International Government

Weeds in Australia - Hydrilla verticillata
Australian Government. Department of the Environment and Energy.

State Government

Encycloweedia: Data Sheet - Hydrilla, Egeria, and Elodea
California Department of Food and Agriculture.
See also: Included on California's noxious weed list; see Encycloweedia: Program Details for additional resources

Noxious Weed Species - Hydrilla
Colorado Department of Agriculture. Conservation Services Division. Noxious Weed Program.

Weed Alerts: Hydrilla
Florida Fish and Wildlife Conservation Commission.

Invasive Plants in Pennsylvania: Hydrilla (PDF | 114 KB)
Pennsylvania Department of Conservation and Natural Resources.
See also: Invasive Plant Fact Sheets for plant species (trees, shrubs, vines, herbs and aquatic plants) that have impacted the state's natural lands

Field Guide: Invasive - Hydrilla
Missouri Department of Conservation.
See also: Problem Plant Control (scroll to Invasive Plants section) for more information to help you identify and control most common invasive plants in Missouri

Class A Noxious Weed: Hydrilla
Washington State Noxious Weed Control Board.


Plant Profile: Hydrilla Verticillata
University of Florida. IFAS. Center for Aquatic and Invasive Plants.

Maine Invasive Plants Bulletin: Hydrilla
University of Maine. Cooperative Extension.
See also: Maine Invasive Plants & Entire Series for entire series of 22 fact sheets and invasive plants brochure (available in HTML/PDF or for purchase)

Invasive Plant Fact Sheet - Hydrilla (Nov 2011; PDF | 86 KB)
University of Pennsylvania. The Pennsylvania Flora Project of Morris Arboretum.
See also: Invasive Plant Fact Sheets for additional invasive plants in Pennsylvania

Factsheet: Hydrilla (PDF | 416 KB)
Pennsylvania State University. Pennsylvania Sea Grant.
See also: Aquatic Invasive Species: Resources for additional species information

Invasive Species Fact Sheets - Hydrilla
University of Wisconsin Sea Grant Institute.


Noxious Weed Information - Hydrilla
Colorado Weed Management Association.

Maine's Interactive Field Guide to Aquatic Invaders and Their Native Look Alikes - Hydrilla
Lake Stewards of Maine.
Special Note: Formerly known as the Maine Volunteer Lake Monitoring Program.


Balciunas, J.K., M. J. Grodowitz, A.F. Cofrancesco and J.F. Shearer. 2002. Hydrilla. In: R. Van Driesche et al. (Eds.), Biological control of invasive plants in the eastern United States (FHTET-2002-04). Morgantown, West Virginia: U.S. Forest Service Forest Health Technology Enterprise Team.

Integrated Taxonomic Information System. Hydrilla verticillata. [Accessed Sep 10, 2014].

Masterson, J. 2007. Hydrilla verticillata. In: Indian River Lagoon Species Inventory. Smithsonian Marine Station.

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Last Modified: Aug 25, 2018
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