Japanese Knotweed

Fallopia japonica


Size: Can grow up to 2m tall

Native to: Japan, China and Korea

Introduced to the UK: By 1850 a specimen was donated to the Royal Botanic Gardens in Kew by European adventurer Philipp Franz von Siebold.

When To See

Late spring to autumn, flowers produced in late summer


Often grows into dense thickets common in urban areas, such as river banks, railways, roadsides and waste land. It out-competes native flora, and on river banks can contribute to bank erosion and increase the likelihood of flooding.

How To Identify

Use our picture based online app to help you identify this plant, click here.

Leaves are lush green coloured, shovel or heart shaped, up to 15cm in length, and occur alternately in a zig zag pattern along the stems. Stems, when grown, are bamboo-like canes with purple flecks and regular nodes. Flowers are small cream or white racemes.

How It’s Treated

Most often repeated spraying with approved herbicides over the course several seasons.

Large shovel shaped leaves

Grows into dense thickets, often along riverbanks

Seen It?

Been kicking about near your local river or burn and come across one of these species? Not sure? Share it with us at riverlife@forthriverstrust.org, we enjoy chatting about invasive species with you.