水丁香是一年生草本植物，高20-50厘米，茎基本直立，有棱角，略带四方形，基部木质化，暗红紫色。单叶互生。花黄色四瓣。蒴果长1.5-2厘米，微弯，类似小香蕉，所以水丁香也被称为“水香蕉”或“假蕉”，蒴果内有细小的棕黄色种子。

水丁香生长在靠水的地方，一般在稻田旁、沼泽地，生长于热带和暖温带，在中国长江以南各地都有分布，是一种稻田杂草，一般花期为7-8个月，但在温暖的地方一年四季都开放。

水丁香全草可以作为中药，可清热利水，降血压。

维基共享资源中相关的多媒体资源：水丁香

Ludwigia octovalvis is a species of flowering plant in the evening primrose family known by the common name Mexican primrose-willow. Its native distribution is unclear, but can be found in Central America, Australia, South-East Asia, the Middle East, the Central-West African regions and spreads easily to become naturalized. It is also cultivated as an aquatic plant. The plant is known for its anti-ageing properties. The species is sometimes regarded as an invasive species and is classified by IUCN as of Least Concern with stable populations. An adult plant is one meter tall on average but is able to grow taller. and spreads to form mats on the mud, rooting at nodes in contact with the substrate, or floats ascending in the water. Its flowers are yellow in appearance. They are made up of green and red stems. They yield small capsular fruits containing many minute seeds.