Fallopia sachalinensis

Fallopia sachalinensis_giant knotweed_CDFA_cropped
Photo: CDFA

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 — Alert?

CDFA Rating: A*?


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.

Species ID Card

Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.

Weed 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

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

Other Fallopia sachalinensis Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - Distribution map and records of this species in California.
  • EDDMapS - Distribution of this species in North America.
  • Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.
  • Additional photos

    Fallopia sachalinensis_leaves and inflorescences_copyright_DeanKelch(CDFA)
    Fallopia sachalinensis (giant knotweed) leaves and inflorescences. Photo: &#169 Dean Kelch, CDFA
    Fallopia sachalinensis_growth habit_copyright2001_FredHrusa(CDFA)
    Fallopia sachalinensis (giant knotweed) growth habit. Photo: &#169 2001 Fred Hrusa, CDFA