Reynoutria japonica

Reynoutria japonica, “Knotweed” or “Japanese knotweed” in English and “Renouée du Japon” in French, belongs to the Polygonaceae botanical family. Native to Asia, it is a herb growing to 2 m in forests and wetlands.

Several parts of the plant are edible. Cooked young shoots can be used as an asparagus substitute and older stems as a rhubarb substitute.

In traditional Asian medicine, rhizomes and young sprouts are used as laxatives. A decoction is used in the treatment of burn injuries, boils and abscesses, poisonous snakebites, acute hepatitis, appendicitis, traumatic injuries and menstrual irregularities.

Among its main constituents are resveratrol, polysaccharides, flavonoids, quinones and large amounts of condensed tannins. Roots and leaves contain stilbenes, flavonoids, anthraquinones, coumarins, essential oils.

• English name Asian knotweed
• French name Renoué du Japon