Asiatic knotweed

Fallopia japonica × sachalinensis (= Fallopia ×bohemica)

Asiatic knotweed

Asiatic knotweed

Legal Status: Unwanted Organism - BNZ
Status in New Zealand: Established
Organism: Land plants

Other Common names: Japanese knotweed, Mexican bamboo


Polygonum cuspidatum, Polygonum reynoutria, Fallopia japonica, Fallopia japonica x sachalinensis, Fallopia x bohemica


Asiatic knotweed is an upright shrublike herbaceous perennial that can rapidly grow to 3 m in height. It has red-purple shoots which appear early in spring but, as the canes grow, the leaves unfurl and the plant turns green. The mature canes are hollow and have a characteristic pattern of purple speckles. The leaves are long and triangular (15 x 10 cm) and pointed at the tip, with a characteristic flattened leaf base. In late summer it produces masses of creamy white flowers.


Once established, Asiatic knotweed forms dense stands that shade and crowd out all other vegetation, displacing native flora and fauna.

What to do

Contact your regional council to determine the status of this species and responsibility for control and/or advice on control.

Page last updated: 14 January 2010