Reynoutria

Reynoutria is a genus of flowering plants in the Polygonaceae, also known as the knotweed or buckwheat family. The genus is native to eastern China, Eastern Asia and the Russian Far East, although species have been introduced to Europe and North America. Members of the genus, including R. japonica (Japanese knotweed) and its hybrid with R. sachalinensis, are highly invasive plants.

==Description== Species placed in the genus Reynoutria are robust erect perennial plants, growing from rhizomes. They are usually monoecious, with mostly bisexual flowers, but also some unisexual flowers. The petals of the flowers are dry and paperlike when mature. The fruits are achenes with threefold sharp edges. The inflorescence is in the form of a panicle. The flowers have separated triangular stigmas with fringes (fimbriate) borne on long divided styles.