Elodea is a genus of eight species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog's-bit family (Hydrocharitaceae), Elodea is native to the Americas and is also widely used as aquarium vegetation and laboratory demonstrations of cellular activities. It lives in fresh water. An older name for this genus is Anacharis, which serves as a common name in North America.

The introduction of some species of Elodea into waterways in parts of Europe, Australia, Africa, Asia, and New Zealand has created a significant problem and it is now considered a noxious weed in these areas.

Species

1. Elodea bifoliata H.St.John – Canada (AB, SK), W United States (OR + CA to NM + MN)
2. Elodea callitrichoides (Rich.) Casp. – Argentina, Uruguay
3. Elodea canadensis Michx. – most of United States + Canada
4. Elodea densa (Planch.) Casp.
5. Elodea granatensis Bonpl. – much of South America
6. Elodea heterostemon (S.Koehler & C.P.Bove) Byng & Christenh.
7. Elodea najas (Planch.) Casp.
8. Elodea nuttallii (Planch.) H.St.John – much of United States + Canada
9. Elodea potamogeton (Bertero) Espinosa – Chile, Peru, Bolivia, Ecuador

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