[ecos.fws.gov] Habitat: The plant grows in areas that were once associated with glacial potholes and former river oxbows that flood in the spring, but usually dry at least partially by late summer. It is often found in shallow water (1 - 2 meters) and on the edges of deep ponds that are partially surrounded by deciduous trees such as black cottonwood and aspen. (link added by Mary Ann Machi)