Reynoutria japonica
- Photographs and information on Japanese Knotweed.
- http://www.plant-identification.co.uk/skye/polygonaceae/reynoutria-japonica.htm

Japanese Knotweed Alliance
- Information on the problem of Japanese knotweed and the concept of natural (biological) control using FAQs, links and updates.
- http://www.cabi-bioscience.org/html/japanese_knotweed_alliance.htm

Polygonum cuspidatum - Japanese Knotweed
- Image, description, and invasiveness.
- http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua015.html