Ludwigia hexapetala

Photo courtesy Joseph DiTomaso

Synonyms: Jussiaea grandiflora (M. Michelli) Greuter & Burdet; Jussiaea repens L var. grandiflora M. Michelli; Jussiaea uruguayensis Camb.; Ludwigia uruguanyensis (Camb.) Hara var. major (Hassler) Munz

Common names: creeping waterprimrose; Uruguay waterprimrose

Ludwigia hexapetala (Uruguay water-primrose) is an aquatic plant (family Onagraceae) that forms dense mats in waterways, reaching above and below the water surface. This dense growth impedes water movement, blocks the growth of native plants, and reduces available habitat for waterbirds and fish. Although this species has been naturalized in California for at least 25 years, it has grown exponentially in the past several years, leading to increased concern over its impacts on waterways. Pieces of Uruguay water-primrose mats can catch on boat and other watercraft that then spread plants to new areas.

Cal-IPC Rating: High

Cal-IPC Assessment

Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

  • Blair M.D., C. E. (2006). Invasive aquatic weeds: Implications for mosquito and vector management activities. Cal-IPC Symposium. Rohnert Park, CA.
  • McNabb, T. J. and J. Meisler (2006). Two years of Ludwigia control in the Laguna de Santa Rosa process and progress. Cal-IPC Symposium. Rohnert Park, CA.
  • Meisler, J. A. (2005). Control of water primrose (Ludwigia hexapetala) in a freshwater wetland. California Invasive Plant Council Symposium 2005. Chico, CA.
  • Verdone, L. (2003). Creeping water primrose (Ludwigia hexapetala) in the Laguna de Santa Rosa. California Invasive Plant Council Symposium 2003. Kings Beach, California, CA.
  • Verdone, L. (2004). Creeping water primrose (Ludwigia hexapetala): The ecology and impacts of an invasive aquatic plant in the Laguna de Santa Rosa. California Invasive Plant Council Symposium 2004. Ventura, CA.

Other Ludwigia hexapetala Information

  • CalPhotos - Images of plants taken mostly in California.
  • CalFlora - Distribution information based on submitted observations and herbarium specimens.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.