Fallopia is a genus of roughly 12 species of flowering plants in the family Polygonaceae (the buckwheat or knotweed family), placed in the order Caryophyllales. The genus was first formally described by the French botanist Michel Adanson in 1763, who distinguished it from the closely related genus Polygonum. Its taxonomic history has been unusually turbulent: it was repeatedly subsumed into a broadly defined Polygonum by later authors including Meissner (1856) and Bentham and Hooker (1880), and for much of the twentieth century the question of whether to include the genus Reynoutria within Fallopia remained unresolved. Molecular phylogenetic studies have since confirmed that Fallopia sensu stricto is a natural group distinct from both Polygonum and Reynoutria.
Plants in the genus grow as annual or perennial vines, lianas, shrubs, or subshrubs. They differ from the related genus Duma in lacking thornlike branch tips. Flowers are bisexual (occasionally the plants are dioecious), arranged in racemes, and bear tepals that become dry and papery at maturity. Extrafloral nectaries are present. Styles are short, with partially fused stigmas forming a compact head. The fruits are achenes with three sharp edges — a characteristic feature shared with several other polygonaceous genera.
The genus is native across much of the Northern Hemisphere, spanning the majority of Eurasia, North Africa, and central and eastern North America. Numerous species have been introduced beyond this range, appearing in eastern and southern Africa, Mexico, and parts of South America. Notable members include Fallopia convolvulus (black-bindweed), a widespread arable weed across Europe and Asia; Fallopia dumetorum (copse bindweed), found in hedgerows and forest margins across Eurasia; and Fallopia aubertii (silver lace vine), a vigorous ornamental climber originating in China. Several former members of the genus, including the highly invasive Japanese knotweed (now Reynoutria japonica) and giant knotweed (Reynoutria sachalinensis), have been reclassified following phylogenetic revision.
Etymology
The genus name Fallopia honours the Italian Renaissance botanist and anatomist Gabriele Falloppio (latinised as Fallopius), who served as superintendent of the botanical garden at Padua and is regarded as one of the founders of modern anatomy. The name was applied by Michel Adanson in 1763 without explicit explanation; the connection to Fallopius is attributed by later commentators.
Distribution
Fallopia species are native to much of the Northern Hemisphere, including most of Eurasia, North Africa, and central and eastern North America. Several species have been widely introduced beyond their native range into eastern and southern Africa, Mexico, and parts of South America.
Ecology
Fallopia species serve as larval food plants for certain Lepidoptera. Coleophora therinella, a small moth, has been recorded feeding on Fallopia convolvulus. Extrafloral nectaries on the plants may attract additional invertebrates.
Taxonomy Notes
The genus Fallopia was described by Michel Adanson in 1763 and has a complex synonymic history. It was repeatedly merged into a broadly circumscribed Polygonum by nineteenth-century authors, and the question of whether Reynoutria should be included within Fallopia was not settled until molecular phylogenetic work confirmed the separation of the two groups. The Flora of North America (2005) treated Reynoutria within Fallopia, while the Flora of China (2003) kept them separate; current consensus (Plants of the World Online, October 2025) accepts approximately 12 species in Fallopia, with the Reynoutria species — including the invasive Japanese knotweed — segregated out.
