Undaria pinnatifida

Photo courtesy Carol Thornber, Univ. Rhode Island

Common names: Japanese kelp; wakame; Asian seaweed

Undaria pinnatifida (wakame) is an annual algae (family Alariaceae) first recorded in several estuaries in California in 2000. Wakame is native to Japan, where it is consumed for its food value and as a nutritional supplement. In California, wakame usually cannot compete with native perennial brown algae, but it may colonize estuaries rapidly if native algae are not present. Hence, wakame occurs in high densities only in recently disturbed areas. Although it does not appear to have serious impacts in California, it has been a very serious invader in New Zealand.

Rating: Limited

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

    • Anderson, L. (2003). Aquatic weeds: Policy, prevention, and control. California Invasive Plant Council Symposium 2003. Kings Beach, CA.
    • Thornber, C., B. Kinlan, et al. (2002). Invasion ecology of the Japanese alga Undaria pinnatifida in California. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
    • Tu, M. and J. M. Randall (2002). 2002 Red alert! New introductions and recent expansions in California. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
    • Tu, M. and J. M. Randall (2003). 2003 Cal-IPC red alert! New invasions, recent expansions, and a few others to be on the look-out For. California Invasive Plant Council Symposium 2003. Kings Beach, CA.

    Cal-IPC News Articles

    • Thornber, C., B. Kinlan, et al. (2002). Invasive ecology of the Japanese alga Undaria pinnatifida in California.
    • Tu, M. and J. M. Randall (2002). 2002 Red Alert! New introductions and recent expansions in California.
    • Tu, M. and J. M. Randall (2003). 2003 Red Alert! New introductions and recent expansions in California.