The NWIPC's 12 Most Unwanted Weeds
Giant and Japanese knotweeds
Japanese Knotweed is a perennial herb with round and hollow (bamboo-like) stems and wide leaves pointed at the tip. Leaves are darker green above and lighter green below. Flowers arise from leaf axils and are greenish to white in colour. This species can grow to 3 m tall and can form very dense thickets.
Giant Knotweed is very similar to Japanese knotweed, but is much larger. It can grow to 6 m tall. While leaves of the Japanese knotweed may be up to 15 cm long, those of Giant knotweed are 20 – 40 cm long.
Himalayan knotweed is also similar in appearance and has been identified in BC.
Other similar species: Himalayan balsam is an annual herb with hollow, jointed stems that are green to purplish in colour. Flowers are slipper-like, pink to purple in colour, but sometimes white. Leaves are green, serrated and stalked, originating only from joints on the stem.
Photo Credit: NWIPC