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You are here: Home / Aquatic Species / Species Profiles / Hydrilla
Aquatic Species
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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)

Impacts: 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

Aquatic Nuisance Species Task Force.

Invasive Plants of California's Wildlands - Hydrilla verticillata
California Invasive Plant Council.
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.


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 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.

Northeast Aquatic Nuisance Species Panel.

Texas Invasives Database - Hydrilla verticillata

Invasive Species Compendium - Hydrilla verticillata
CAB International.

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

Federal Government

Germplasm Resources Information Network (GRIN) - Hydrilla verticillata
USDA. ARS. National Genetic Resources Program.

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.

International Government

Weeds in Australia - Japanese Honeysuckle (Lonicera japonica)
Australian Government. Department of the Environment.

State Government

Encycloweedia: Data Sheet - Hydrilla, Egeria, and Elodea
California Department of Food and Agriculture.
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.

Hydrilla - Weed Alert (PDF | 739 KB)
Florida Fish and Wildlife Conservation Commission.

Invasive Plants in Pennsylvania: Hydrilla (PDF | 114 KB)
Pennsylvania Department of Conservation and Natural Resources.

Hydrilla - Non-Native Freshwater Plants
Washington State Department of Ecology. Water Quality Program.

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.

Aquatic Invader Toolkit - Hydrilla (PDF | 673 KB)
Illinois-Indiana Sea Grant.

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 Atlas of the MidSouth - Hydrilla
Mississippi State University. GeoResources Institute.

Hydrilla (PDF | 86 KB)
University of Pennsylvania. Morris Arboretum.

Fact Sheet: Hydrilla (PDF | 259 KB)
Pennsylvania State University. Pennsylvania Sea Grant.

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


Noxious Weed Information - Hydrilla (A List)
Colorado Weed Management Association.

The Quiet Invasion: A Guide to Invasive Species of the Galveston Bay Area - Hydrilla, Waterthyme, Florida Elodea
Galveston Bay Estuary Program (Texas).

Maine's Interactive Field Guide to Aquatic Invaders and Their Native Look Alikes - Hydrilla
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: May 19, 2016
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