Fallopia sachalinensis

Photo courtesy Joseph DiTomaso

Synonyms: Polygonum sachalinense; Reynoutia sachalinensis

Common names: giant knotweed; sakhalin knotweed; sacaline

Fallopia sachalinensis (Sakhalin knotweed) is a perennial forb/herb (family Polygonaceae). Plants grow vigorously and create dense colonies that exclude other vegetation. Established colonies are extremely difficult to eradicate. It inhabits disturbed moist sites, roadsides, riparian and wetland areas. Plants typically grow in open, sunny areas on moist soils in cool temperate climates. Very little of this species occurs in California. It is a much bigger problem in the Northwestern US.

Cal-IPC Rating: Moderate

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

  • Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

  • Crockett, R. P. and M. L. Krebsbach (2004). The new “JK Injection Tool” for control of knotweeds and other hollow-stem plants growing in sensitive wetland sites. California Invasive Plant Council Symposium 2004. Ventura, 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 Fallopia sachalinensis Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • CDFA - California official noxious weeds.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.