California Invasive Plant Council

Fallopia ×bohemica

Common names: Bohemian knotweed (X Japanese and Giant)

Fallopia ×bohemica (Bohemian knotweed (X Japanese and Giant knotweed) is a perennial (family Polygonaceae) with white flowers and broad leaves found in northwestern California. It is native to Japan. It favors grasslands and riparian and bottomland habitat. It spreads via rhizomes and seeds and is dispersed along watercourses and in garden waste.

Cal-IPC Rating: Watch

CDFA Rating: A*

Cal-IPC Assessment

Plant Risk Assessment - An evaluation of the potential for a plant to be invasive in California.

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

• CDFA expands noxious weed list and revises process. Kelch, Dean. Vol 23, Issue 2

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.

• 2019 Weed Alerts. Burger, Jutta; Price, Bob (2019)

Other Fallopia ×bohemica Information

• Calflora - See the distribution of this species on Calflora's map of California.
• USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.