- Myriophyllum aquaticum is an herbaceous, rooted, submerged to emergent plant that invades aquatic habitats throughout much of the United States. Stems are stout and blue-green in color.
- Leaves are abundant, whorled, pinnately compound, and finely dissected. Submersed leaves are 0.6-1.4 in. (1.5-3.5 cm) long and have 20 to 30 divisions per leaf. Emergent leaves are 0.8-2 in. (2-5 cm) long, less divided and greener than the submersed leaves.
- As only female plants occur in North America, reproduction occurs vegetatively. Inconspicuous flowers are formed in the axils of the emergent leaves in the spring (sometimes fall).
- No fertile fruit is known to be produced in the United States.
- Ecological Threat
- Myriophyllum aquaticum's potential range is yet to be determined. In more southern regions, this plant forms monocultures that clog waterways, impeding recreational and commercial boating activities. These monocultures also disrupt the growth of native aquatic plants and provide breeding areas for mosquitoes. Myriophyllum aquaticum is a common water garden plant, which has the potential to escape into local waterways. Control of this plant is extremely costly.
- Global Invasive Species Database. 2011. Invasive Species Specialist Group (ISSG) of the IUCN Species Survival Commission
- King County Department of Natural Resources and Parks Water and Land Resources Division
- University of Florida, IFAS Extension, Center for Aquatic and Invasive Plants
- Oregon Department of Agriculture Plant Programs, Noxious Weed Control
- Washington State Noxious Weed Control Board
- University of California, Jepson Flora Project
- Invasive Plant Atlas of New England (IPANE)
- Invasive Plant Atlas of the MidSouth (IPAMS)
- Texas Invasive Plant and Pest Council
- California Invasive Plant Council
- USDA NRCS PLANTS
- USDA ARS GRIN