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.

Rating: High

Cal-IPC Resources

  • 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.
  • CalWeedMapper - Statewide maps, climate models, and reports.
  • Cal-IPC News - Our quarterly newsletter. Each issue is available as a pdf.
  • Cal-IPC Symposium Proceedings - Presentations and papers from our annual Symposium.
  • Don't Plant a Pest! - Select your region to find non-invasive alternatives to ornamental species. Also see our statewide brochure on trees.

    Other Resources

    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.

    Cal-IPC News Articles

    • Meisler, J. (2009). Lessons from Ludwigia control in Sonoma County. Cal-IPC News. 17: 4,5,12.
    • Burkhart, B. and M. Kelly (2005). Which weeds dominate southern California urban riparian systems? Cal-IPC News. 13: 4-5,12.
    • Charles E Blair, M. (2006). Invasive aquatic weeds: Implications for mosquito and vector management activities. Cal-IPC Symposium, Rohnert Park, CA, California Invasive Plant Council.
    • 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, California Invasive Plant Council.
    • Verdone, L. (2004). Creeping water primrose (Ludwigia hexapetala): the ecology and impacts of an invasive aquatic plant the Laguna de Santa Rosa. Cal-IPC.