Reynoutria is a genus of flowering plants in the family Polygonaceae. 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.
Species placed in the genus Reynoutria are robust erect perennial plants, growing from rhizomes. They are usually monoecious, with mostly bisexual flowers, but ...