Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.
European frogbit (Hydrocharis morsus-ranae) is a floating-leaved aquatic plant native to parts of Europe and Asia that is popular in water gardens. The history of invasiveness for H. morsus-ranae is high; it has been introduced in Canada and the United States as an ornamental plant. H. morsus-ranae is capable of supplanting native plants to create monocultures in some areas. Those monocultures remove habitat and food sources for native animals and may have an impact on water quality. Dense, invasive populations also hinder commercial and recreational uses of waterways. The climate match is high. The areas of highest match are centered on already established H. morsus-ranae populations in the Northeast, Great Lakes, and Pacific Northwest. However, the climate match did show areas of high match that do not have currently established populations, indicating that the climate exists to support further spread of this species. The certainty of assessment is medium. The overall risk assessment category is high.
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High Risk
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