Ecological Risk Screening Summary - South American waterweed (Elodea callitrichoides) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.

The South American waterweed (Elodea callitrichoides), is a rooted, aquatic plant native to Uruguay and Argentina. The history of invasiveness for E. callitrichoides is Data Deficient. Elodea callitrichoides is sometimes in trade for aquarium use. The species has been reported as introduced throughout Europe, however genetic studies have recently found the populations in Belgium and France to be misidentifications of a congener. The remaining established populations in Great Britain and Austria have very little information available. Introductions reported to Canada and the United States are most likely misidentifications. There was some general impact information for Elodea species as a group in Europe. The climate match is high for the contiguous United States. The certainty of assessment is Low due to lack of information and misidentifications. The overall risk assessment category for Elodea callitrichoides in the contiguous United States is Uncertain.