- Egeria densa is a submersed aquatic plant that invades freshwater systems throughout much of the United States. Often confused with hydrilla, Egeria densa has a smooth midrib on the underside of the leaf, whereas hydrilla has small teeth.
- The finely serrated leaves are usually less than 1 in. (2.5 cm) long and occur in whorls of 3-6.
- The flowers, which bloom above the surface of the water, are white with three petals.
- Outside of its native habitat, Egeria densa only reproduces vegetatively. Special double nodal regions can produce lateral buds, branches and roots. Only a double node can produce a new plant when it breaks off from the parent plant.
- Ecological Threat
- Egeria densa invades both still and flowing water ecosystems including lakes, ponds, ditches, and rivers. It can form dense stands that crowd out native vegetation and reduce the area's value as fish habitat. It can also interfere with recreational activities such as fishing and swimming. This plant was first introduced into the United States in the late 1800s as an aquarium plant.
Global Invasive Species Database. 2011. Invasive Species Specialist Group (ISSG) of the IUCN Species Survival Commission 
Washington State Noxious Weed Control Board 
Invasive Plant Atlas of New England (IPANE) 
University of California, Jepson Flora Project 
Washington State Department of Ecology 
CABI Invasive Species Compendium 
Oregon Department of Agriculture 
California Invasive Plant Council 
University of Maine Extension 
USDA NRCS PLANTS 
USDA ARS GRIN 
Images from Bugwood.org