Persicaria chinensis aka Chinese Knotweed

Persicaria chinensis is also known as Chinese knotweed. It belongs to the plant family Polygonaceae. It is native to tropical and subtropical parts of Asia. Useful Tropical Plants records it from Korea to southern Asia. Its range takes in China, Japan, India, Nepal, and Bhutan. It also grows in parts of mainland Southeast Asia. Its range spans parts of island Southeast Asia too. Its older name is Polygonum chinense. Both names refer to the same species. It is not native to Britain or Ireland.

This plant lives for many years and most often climbs. Its many branches grow from stout rhizomes, or underground stems. Useful Tropical Plants gives a height of about 3.3 feet [1 metre]. Stem lengths vary much more. They may reach 1–20 feet [0.3–6 metres]. These lengths are not a range for height in gardens. The lower stems can grow woody with age. At higher sites, plants often stay small and stand upright. Its form can thus vary across its wide range.

In the wild, it grows in scrub and at woodland edges. It also grows in open woods and by rivers. Records place it in tea plantations and those growing Cinchona. In Malesia, it grows on damp waste ground. It grows in lowlands and at mountain sites. Records span sea level to about 10,800 feet [3,300 metres]. Its climates range from temperate Korea to tropical southern Asia. These records do not show its garden hardiness. Nor do they set its light or water needs in gardens.

Insects carry pollen between the flowers. As seeds ripen, the tepals turn fleshy and blue-black. These flower parts wrap the seeds and are edible. People eat them raw for their sour taste. They also pickle tender leaves and young shoots for food. The source gives no evidence for eating this species’ seeds alone. It lists no known hazards. This does not mean the plant is safe for pets.

People gather this wild plant for food and medicine. Some also grow it for its looks. Past uses include making remedies for wounds and skin complaints. Such records show use, not proof that these treatments work. The supplied evidence gives no pest or disease details for this species. It gives no firm bloom season or spread in gardens.