Brazilian Elodea

Photo credit: Robert Vidéki, Doronicum Kft., Bugwood.org

(Egeria densa)

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If you believe you have found this species anywhere in Pennsylvania, please report your findings to iMapInvasives by submitting an observation record.

Species at a Glance

Brazilian elodea is a submerged aquatic perennial that can reach lengths of 3 m (10 ft) or more, and can survive either rooted or free-floating in depths up to 6.1 m (20 ft). Because of its showy flowers and oxygen generating capabilities, it is widely used as an aquarium plant and is still sold today under its alias “Anacharis”. All introductions in the United States appear to be male plants.

Identification

Leaves: Bright to dark green; densely arranged in whorls of 4-6 leaves per node, although some lower leaves may occasionally occur in opposite pairs or in whorls of three leaves. The leaves are robust and blade shaped, 1-3 cm

(0.4-1.2 in) long and 5 mm (0.2 in) wide. Very fine teeth on the leaf margins are only visible with magnification.

 

Flowers: Large showy flowers with three white petals, a yellow center, and three green sepals. They emerge above or at the water’s surface on slender stalks projecting from leaf axils near the stem tips.

 

Stems/Roots: Roots form irregularly along the stems from “double nodes,” which are areas where two whorls appear to be joined.

Similar Species

Brazilian elodea may be confused with the invasive plant Hydrilla verticillata and the native plant American elodea (Elodea canadensis). Hydrilla has small sharp teeth on the edges of the leaves and spines or conical bumps on the undersides. Hydrilla also produces tubers; Brazilian elodea does not. American elodea has only 2-3 leaves per whorl and is smaller, usually less than 2.5 cm (1 in) long. These species also differ significantly in their flowers, with Brazilian elodea being the only one to produce large, attractive white flowers with three petals.

Habitat

In its native range, Brazilian elodea lives in slow-moving and shallow waters. As an invader, it can be found in lakes, ponds, sluggish rivers, and streams. It grows best in enriched, somewhat acidic lakes, and prefers substrates of sand, mud, or stone.

Spread

In the past, Brazilian elodea spread mostly due to release by aquarium owners and water gardeners. Since all plants in the United States are male, they can reproduce only vegetatively by plant fragments. Fragments can attach to recreational boats, trailers, and equipment and be spread to new water bodies. Once established, Brazilian elodea has the ability to cover 100 acres of water per year.

Distribution

Brazilian elodea is native to South America, specifically Brazil and coastal regions of Argentina and Uruguay. It is found to be invasive in several states in the U.S., including all states in the Mid-Atlantic region.

 

Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.

Environmental Impacts

Brazilian elodea grows rapidly, up to 30 cm (11.8 in) in length per day in ideal conditions. It forms mats at the water’s surface, which crowd out native species, impede aquatic recreational activities such as boating and fishing, destroy water quality, and make poor habitat for fish. Fragmented pieces can also clog water intake pipes.

Note

Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).

The Pennsylvania iMapInvasives Program is a partnership of the Western Pennsylvania Conservancy, the Pennsylvania Natural Heritage Program, and NatureServe.

Funding for Pennsylvania iMapInvasives is provided by the Great Lakes Restoration Initiative.

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