Chinese Knotweed

Persicaria chinensis (synonym Polygonum chinense),commonly known as creeping smartweed or Chinese knotweed, is a plant species from the family Polygonaceae. It is widespread across China, Japan, the Indian Subcontinent, Indonesia, Malaysia, and Vietnam.] It is a common plant in Malaysia and Vietnam, where it is used in herbal remedies, such as for the treatment of dysentery, enteritis, and sore throat. It is a weed in some coastal areas of New South Wales and Queensland in Australia.

Persicaria chinensis is a perennial climber that grows to 2–3 m high. Its stems are glabrous and red-brown, with longitudinal stripes. Its leaves have oval blades, are 4–8 cm long and 3–5 cm wide, with pointed apex and round or nearly cordate base. Its cymes emerge at terminals, and are 5–7 cm long, with small white or pink flowers.

Why Should You Care About This Pest?

Chinese knotweed (Persicaria chinensis) is a rapidly growing perennial bushy vine that can smother other plants, including trees. It could impact forestry, orchards and nurseries and become a problem in your home garden. It can regenerate quickly from small plant fragments and can spread via contaminated gardening tools and machinery such as lawnmowers. This pest may be shared by people among the community who grow the plant for traditional medicinal purposes and are not aware of the problems associated with Chinese knotweed. However, imported traditional Chinese medicinal products with Chinese knotweed can be purchased legally from stores without endangering our environment. 

Where Is It Found?

Chinese knotweed currently has a limited distribution, but there is potential for the pest plant to establish itself more widely as it can tolerate a variety of conditions. 

What Does It Look Like?

This bushy herbaceous vine can grow up to 1 metre tall if it is not climbing over other plants or structures. Stems are reddish/pinkish in colour and leaves have a conspicuous V-shaped blotch. Flowers clusters are cream/pink coloured. 

Chinese knotweed has pinkish stems; soft, serrated leaves (4cm to 16cm long) with a conspicuous, pale, V-shaped blotch; and clustered cream or pink flowers. When not climbing over other plants or structures, it grows up to 1m tall.