Ludwigia palustris

About

Ludwigia palustris is a species of flowering plant in the evening primrose family known by the common names marsh seedbox, Hampshire-purslane and water purslane. This is an aquatic or semiaquatic perennial herb which grows in moist to wet to flooded areas. It is sometimes a weed. The species epithet palustris is Latin for "of the marsh" and indicates its common habitat.

Summary from Wikipedia