水龙（学名：Ludwigia adscendens）为柳叶菜科丁香蓼属的植物。

多年生草本；根状茎很长，横生泥中，具有白色呼吸根；长椭圆状倒披针形至倒卵形叶片，顶端钝成圆，基部渐狭成柄；夏季开白色或淡黄色花，单生于叶腋，花柄与子房相连处有鳞片状小苞片两枚；圆柱形蒴果。

Ludwigia adscendens, with common name water primrose, is a species of flowering plant in the evening primrose family. Its native distribution is unclear. It is now a common weed of rice paddies in Asia and occurs also in Australia and Africa, but may have originated in South America.