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Washington State Weeds

Brazilian Elodea

Brazilian Elodia

Egeria densa • Class B

Family Name: Hydrocharitaceae (hy-droh-KAIR-i-ta cee-ee)
Common: Frog’s-bit family, Fresh and saltwater Aquatic herbs
Genus: Egeria (ee-JEE-ree-uh) 
Meaning: Named for a Roman nymph or goddess and adviser to Numa Pompilius
Species: densa  (DEN-suh)
Meaning: Compact, dense

Brazilian Elodea looks similar to the native Elodea Canadensis (waterweed), but is much larger.

Plants grow underwater and sometimes as a free floating mass.

Stems are erect, cylindrical and about 1/10 of an inch in diameter.

Leaves are thin with slightly serrated edges and grow in whorls of 3 to 6.

 Why Is it a Noxious Weed?

Its dense underwater growth obstructs water flow, interferes with irrigation projects, hydroelectric utilities, and urban water supplies.

It slows water traffic, interfering with recreational activities such as boating, swimming, and fishing.

It reduces the diversity of native plant seeds in lake bottoms, and increases sediment accumulation beneath the weed beds.

Where Does it Grow?

Brazilian elodea can be found in open ponds and lakes, streams, and wetlands; in depths of up to 20 feet.

In lakes where it is established, it out-competes Eurasian water milfoil and is more difficult to control than milfoil. Harvesting tends to spread the plant and many aquatic herbicides do not effectively control its growth.


It reproduces by roots and plant fragments. Stem fragments can take root in bottom mud or remain as free-floating mats.

Plant fragments are spread by flooding, waterfowl, and human activities like fishing and boating.

Control Options:

 The Triploid grass carp can be helpful as a biocontrol agent in cetain specific situations.  For information about the biological control of Brazilian Elodea, see the WSU Extension Integrated Weed Control Project


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


Since Brazilian Elodea is an aquatic plant, the use of an herbicide formulated for aquatic settings is required. Please note that aquatic herbicides are restricted for use in Washington State to licensed applicators only.

More Information: For more information on this noxious weed  Download our Flyer or visit Washington State Noxious Weed Control Board Here
More Pictures:  


brazilian elodiabrazilian elodia