|Species:||Egeria densa Planch, (formerly called: Elodea densa (Planchon) Caspary), Brazilian elodea, anacharis, giant elodea|
This non-native plant is commonly sold as an aquarium plant in most of the United States and in Canada, but it is illegal to sell in Washington. Brazilian elodea is an underwater and sometimes floating perennial that can form tangled masses near the water surface. Densely-packed green leaves are arranged in whorls of 4-6 around the stem.
Leaf: Bright to dark green leaves, 2-4 cm long and 2-5 mm wide, have minutely toothed edges and are closely spaced in whorls of 4-6 in the upper part of the plant, becoming more widely-spaced whorls of 3 at the stem base.
Stem: Up to 3 m in length. Leaves occur along the entire length of the stem.
Flower: Fragrant white flowers have a yellow center with three, 7-9 mm long petals. Flowers float on the water surface and are attached at the base of leaf whorls by long slender stalks (to 6 cm). Two to three flower stalks may arise from the same whorl. Male and female flowers are produced on separate plants, but only male plants are found in the United States. The plant flowers from late spring to early fall.
Fruit: Fruits and seeds have not been observed outside of its native range.
Root: Fibrous. Can produce white advantitious roots along the stem.
Propagation: Because only male plants are found here, propagation is from stem fragments and by collapsed stems that sprout roots and form the base of new plants. Dormant shoots develop in the fall and overwinter in the sediment.
Importance of plant: Crowds out native species. Eaten by wildlife, although not preferred forage.
Distribution: South American native. Introduced to North America via the aquarium trade. Occurs in some Northwest lakes and rivers and is considered to be a nuisance.
Habitat: Lakes, ponds, sloughs, streams.
May be confused with: Hydrilla (Hydrilla verticillata), another non-native invasive species. Hydrilla has tubers, the leaves are more spiny in appearance and usually occur in whorls of 5. Common waterweed (Elodea canadensis) has smaller leaves in whorls of 3.
Line Drawings: Egeria densa
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