Issue 6, May 29, 2009

Invasive Species Spotlight--Brazilian Elodea

Native to southeastern South America, Brazilian elodea (Adobe PDF) has spread from its native habitat with the aid of its usage as an aquarium plant. The problem occurs when this plant is released into natural aquatic habitats.

Brazilian elodea can be found growing in open ponds and lakes, old reclaimed quarries, slow-moving streams, and wetlands. It can be found growing at depths of up to 20 feet. Its only primary form of spread is through introductions from unwanted aquarium waste and fragmentation, where a portion of the plant becomes separated from the main plant and floats away or roots in a new area. Elodea is dioecious and all the plants found in the US are thought to be males and is not known to spread through seed production.

Lake invaded by Brazilian elodea.

The plant can grow very rapidly in new areas. They quickly out-compete native plants for space. This aquatic invader can slow down or alter water flow, thereby trapping sediment and creating stagnant pools. It is also a problem for aquatic recreationists, interfering with boating and fishing.

Until recently, in Illinois this invasive plant was positively identified in a few southern counties (Adobe PDF). Last summer, Brazilian elodea was found in a pond in Libertyville (Lake county). During regular pond maintenance, two populations were uncovered.

It can be identified by the leaves and stems. Its leaves grow in whorls around the stem in groups of 4 to 8. They are oblong to linear about 1 inch long and 1/4 inch wide. The margins have very fine serrations that may be difficult to see. Brazilian Elodea may flower from spring and early summer with sporadic flowers up into the autumn. Each flower is held above the water's surface on a fine stalk up to 3/4 of an inch in diameter and white with 3 petals. It can be confused with American Elodea (Elodea canadensis) which can look very similar but has leaves whorled usually in groups of 3's that are only 1/2 inch long.

Brazilian eldoea.

For a neat reference on Brazilian elodea, complete with a species video, visit Weedy Plants of the U.S.

Residents are urged to report suspected infestations and also help stop the spread of aquatic invasives with these simple precautions:

  • Dispose of any excess plants in the trash.
  • Do not release aquatic invasive plants into any waters.
  • Rinse your aquatic garden plants before planting.
  • Keep aquatic plants contained in your water garden.
  • Clean all recreational vehicles, trailers, and equipment before leaving any lake or river, since the plant can "hitchhike" onto such equipment.
  • Visit the Illinois CAPS website for all the latest news on invasive pests in Illinois.--Kelly Estes

    Kelly Estes

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