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.

Cal-IPC Rating: Limited

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.

Weed RIC Management Notes

No Weed RIC Management Notes are available for this species. Check for information on other species in the genus on the Weed RIC site.

Cal-IPC Newsletter Articles

Cal-IPC 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.

Other Undaria pinnatifida Information

  • Calflora - See the distribution of this species on Calflora's map of California.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.