Ludwigia decurrens

Ludwigia decurrens is a species of flowering plant in the evening primrose family known by the common names willow primrose and wingleaf primrose-willow. It is native to the central and eastern United States.
This species is an annual or woody perennial herb growing up to 6 feet tall. It has an erect form and a winged stem. The linear leaves are alternately arranged. The flower has four to five yellow petals.
This plant grows in wet habitat types, often alongside "Polygonum" and "Cyperus" species.
This species has been shown to have allelopathic effects on other plants.