Ludwigia hexapetala, the water primrose, is a herbaceous perennial plant of the family Onagraceae.

Native to Central and South America, its habitat includes the margins of lakes, ponds, ditches, and streams.

It is a noxious invader of aquatic ecosystems in North America.

It occurs naturally in swampier regions, such as those of lakes, ponds, and other areas of low intensity/stagnant water.

It grows in mats of up to three feet tall, and in doing so, it crowds and/or shades out the other, more native species.