Ecological Risk Screening Summary - Wingleaf Primrose-willow (Ludwigia decurrens) - High Risk

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.

Wingleaf primrose-willow (Ludwigia decurrens) is a plant found in saturated soils and in ephemeral ponds. This species has a broad native range across parts of South, Central, and North America, including the southeastern United States. It does not appear to be in commercial trade in the United States or globally, but it is used medicinally in Nigeria. In 2011, L. decurrens was reported from rice fields in Butte County, California, outside its native range in the United States. It was likely present for several years prior to its identification in California and it is now labeled as a noxious weed in the State. L. decurrens has also established outside its native range in the U.S. Virgin Islands and Puerto Rico, although at least one source treats the species as native to Puerto Rico. Outside the United States, Ludwigia decurrens has been reported as established in West Africa (Guinea-Bissau, Guinea, Gambia, Sierra Leone, Benin, Niger, Nigeria, and Cameroon), Asia (mainland China, Taiwan, Japan, the Philippines, India, Sri Lanka), and France. The history of invasiveness is classified as High because the species has significant negative impacts on rice cultivation. However, impacts of introduced L. decurrens on native species remain unknown. The climate match for the contiguous United States is High. Most regions of the United States had medium or high climate match, with low match limited to the Rocky Mountains, the coastal Pacific Northwest, and along the Canadian border from Minnesota to eastern Washington. The certainty of the assessment is High. The overall risk assessment category for Ludwigia decurrens is High.