Fallopia is a genus of about 12–15 species of flowering plants in the buckwheat family, often included in a wider treatment of the related genus Polygonum in the past. The genus is native to temperate and subtropical regions of the Northern Hemisphere. The genus includes herbaceous perennial plants, herbaceous vines, and woody vines. Several species are serious invasive weeds, notably Japanese knotweed in Europe and North America. Fallopia species are used as food plants by the larvae of some Lepidoptera species including Coleophora therinella (recorded on F. convolvulus).