Giant knotweed has very large leaves, up to 40cm long, with a heart shaped base.
Bohemian knotweed (hybrid) has leaves up to 25cm long, with a slightly curved base. Its leaf looks midway between that of a Japanese and giant knotweed leaf.
Himalayan knotweed has lance-shaped leaves, up to 20cm long. They have a red mid-vein. The flowers of Himalayan knotweed are held on red stalks.
There are three other types of knotweed present in Ireland. They all pose the same threats as Japanese knotweed. The three types are: Giant knotweed (Fallopia sachalinensis); Bohemian knotweed (Fallopia x bohemica), which is a hybrid between Giant and Japanese knotweed; and Himalayan knotweed (Persicaria wallichii). The various types can be identified by their different leaf shapes.
If you find Japanese knotweed, DO NOT CUT OR BREAK it! Stem and root fragments can easily regrow as new plants.
DO NOT TRANSPORT Japanese knotweed anywhere. It is illegal to move knotweed waste except to bring it to a licensed waste facility that has been given prior notification.
Any eradication or control of Japanese knotweed must be undertaken by a reputable invasive species control company. Poorly planned treatments will increase the plant’s resistance to future control methods!
If you encounter a knotweed please enter the details into our log.