Brazilian waterweed

Egeria densa Planch.

U.S. Nativity: Exotic
Habit: Aquatic

Synonym(s): Brazilian waterweed, Brazilian elodea, South American waterweed

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.

Identification, Biology, Control and Management Resources

Invasive Plant Atlas of New England - University of Connecticut
Global Invasive Species Database - Invasive Species Specialist Group