Brazilian Elodea

Egeria densa

   

Family: Hydrocharitaceae

Other common names: Brazilian egeria

Weed Class: B

Year Listed: 1993

Native to: South America

Toxic: not known to be

additional photos

 

   

Why is it a noxious weed?

Brazilian elodea is an ornamental aquatic plant that is used primarily for fish aquariums. Infestations can alter aquatic ecosystems, trapping sediment and degrading water quality. It forms dense mats that shade out other native aquatic plants, inhibits water flow, and recreational activities.

How would I identify it?

General Description: Submersed freshwater perennial herb that grows underwater and is sometimes free floating. It forms dense masses of growth near the water's surface.

Flower Description: Brazilian elodea has male and female flowers on separate plants. So far introduced populations only have male flowers. The flowers are white, have 3 petals and are on threadlike stems.

Leaf Description: Lower leaves appear in whorls of 3, and the upper leaves appear in whorls of 4 to 8. They are minutely serrated, linear and bright green.

Stem Description: Stems grow upright until reaching the surface and then branch, forming a dense mat of growth.

Fruit/Seed Description: Only male plants have been found here in Washington, so no seed is produced here.

May be confused with: There is a native elodea that may be confused with Brazilian elodea. Waterweed (Elodea canadensis) is much smaller and less robust. If you need help with identification, contact your county weed coordinator.

How does it reproduce?

Brazilian elodea reproduces by roots and plant fragments.
 

Where does it grow?

Brazilian elodea can be found in still and flowing waters such as lakes, ponds, streams and ditches. Please click here to see a county level distribution map of Brazilian elodea in Washington.
 

How do I control it?

General Control Strategy

Brazilian elodea can be difficult to control. Since it spreads by stem and rhizome fragments, mechanical methods such as cutting, harvesting and underwater tilling are not advisable. These methods can increase the infestation. The entire plant must be removed.

Mechanical Control

Mechanical removal is not advised unless the area is entirely invaded by plants because mechanical methods may increase infestation. Small populations can be carefully handpulled if all plant parts can be removed.

Cultural Control

Small infestations may be controlled with the use of an opaque fabric that blocks light from the plant.

Biological Control

Triploid grass carp does find Brazilian elodea palatable but this method of control can only be used in certain situations.

Herbicide Control

Because herbicide availability and regulation differ between states, we recommend the Washington Department of Ecology website for information on aquatic weed management and herbicides, or contact your county noxious weed coordinator.


 

For more information

 
See our Written Findings for more information about Brazilian elodea (Egeria densa).

Additional Photos


 
 

Brazilian elodea stems

Brazilian elodea infestation

branching pattern

showing stem scale

in flower

submerged growth

    

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