| hydrilla |
USDA PLANTS Symbol: HYVE3 USDA ARS GRIN: 316414 ITIS: 38974 NAPIS: PCHAFBA |
| Hydrilla verticillata (L. f.) Royle | |
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Taxonomic Rank: Liliopsida: Hydrocharitales: Hydrocharitaceae |
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| Synonym(s): Florida elodea, water thyme, waterthyme | |
Hydrilla is a submersed, rooted aquatic plant that can grow in water up to depths of 20 ft. (6.1 m). Plants can survive in depths up to 40 ft. (12 m) in non-turbid water. Leaves are whorled in bunches of 3-8, but most often with whorls of 5. The midribs of the leaves are reddish in color with the undersides having small, raised teeth. Leaves are 0.2-0.8 in. (5-20 mm) long, less than 0.1 in. (2 mm) wide and have serrated margins. Hydrilla forms dense mats at the surface of the water. The dense mats can restrict native vegetation, irrigation practices, recreation, hydroelectric production, and water flow. It can invade most slow-moving or still water systems. Hydrilla is believed to be native to Asia or Africa, although it is widely spread across the globe. It was first introduced into North America as an aquarium plant in the 1950s. Hydrilla can sometimes be confused with Brazilian egeria (Ergeria densa Planch.) and Canadian waterweed (Elodea canadensis Michx.). The leaves of Canadian waterweed occur in whorls of three along the stem and are up to 0.2 in. (5 mm) wide. The midrib of Brazilian egeria is smooth as opposed to the toothed midrib of hydrilla. |
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Identification, Biology, Control and Management Resources
- Global Invasive Species Database - Invasive Species Specialist Group
- Weed of the Week - USDA Forest Service
- Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS
- Identification and Biology of Non-Native Plants in Florida's Natural Areas - University of Florida
- Invasive Plant Atlas of New England - University of Connecticut
- Element Stewardship Abstract - The Nature Conservancy
- Southeast Exotic Pest Plant Council Invasive Plant Manual - SE-EPPC
- Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
- Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service
- Fact Sheet - Pennsylvania Dept. of Conservation and Natural Resources
| Selected Images from Invasive.org | View All Images at Invasive.org |
 Feature(s); tubers Tim Murphy, University of Georgia, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Whole plants out of water Leslie J. Mehrhoff, University of Connecticut, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Chris Evans, River to River CWMA, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); David J. Moorhead, University of Georgia, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Michael Frank, Galileo Group Inc., Bugwood.org Additional Resolutions & Image Usage |
 Infestation; James R. Allison, Georgia Department of Natural Resources, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; David J. Moorhead, University of Georgia, Bugwood.org Additional Resolutions & Image Usage |
 Dispersal; tangled on boat motor Wilfredo Robles, Mississippi State University, Bugwood.org Additional Resolutions & Image Usage |
 Seed(s); Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage |
Taxonomic References:
- USDA, NRCS. 2001. The PLANTS Database, Version 3.1, National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Invasive Listing Sources:
- Connecticut Invasive Plant Working Group
- Delaware Natural Resources and Environmental Control, 2004
- Faith Campbell, 1998. Plants that Hog the Garden: Invasive Plants in the United States. Fine Gardening Online
- Federal Noxious Weeds
- Gulf of Mexico Regional Panel, Aquatic Nuisance Species Annual Report, 2001
- Jackie Poole, Texas Parks and Wildlife Department (personal communication)
- Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
- John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
- Maryland Department of Natural Resources, 1994
- Mid-Atlantic Exotic Pest Plant Council, 2005
- New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture, Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
- Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
- North Carolina Division of Parks and Recreation, Department of Environment and Natural Resources, 1998
- Pacific Northwest Exotic Pest Plant Council, 1998
- USDA APHIS Regulated Pest List
- Vermont Department of Environmental Conservation,
- Virginia Department of Conservation and Recreation, 1999.
- WeedUS - Database of Plants Invading Natural Areas in the United States
- Alabama Invasive Plant Council
- Arizona Noxious Weeds
- California Invasive Plant Council
- California Noxious Weeds
- Colorado Noxious Weeds
- Connecticut Noxious Weeds
- Alachua County Cogongrass Initiative
- Apalachicola Invasive Working Group
- Florida Exotic Pest Plant Council Category I
- Treasure Coast Cooperative Invasive Species Mgmt. Area - EARLY DRAFT
- Georgia Exotic Pest Plant Council Category 1
- Idaho Noxious Weeds
- Massachusetts Noxious Weeds
- Maine Noxious Weeds
- Mississippi Noxious Weeds
- North Carolina Noxious Weeds Class A
- New Mexico Noxious Weeds
- Nevada Noxious Weeds
- Oregon Noxious Weeds
- South Carolina Noxious Weeds
- Tennessee Exotic Pest Plant Council Significant Threat
- Texas Noxious Weeds
- Vermont Noxious Weeds
- Washington Noxious Weeds
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