Polygonum oxyspermum is a coastal species of flowering plant in the buckwheat family. It is native to Europe, primarily along the shores of the Atlantic, the North Sea, and the Baltic Sea, from France and Ireland to Finland and Russia.Online Atlas of the British and Irish flora, Polygonum oxyspermum (Ray`s Knotgrass) It is also naturalized in eastern Canada and in the US State of Maine.Wilde Planten in Nederland en België, Zandvarkensgras in Dutch with photos and global distribution map
Description Polygonum oxyspermum is green or blue-green. Annual, stems prostrate, generally run along the surface of the ground but sometimes do rise above ground level. They can be as much as long. Leaves are up to long. Flowers are green, white or pink, in axillary clusters.Parnell, J. and Curtis, T. 2012. Webb's An Irish Flora. Cork University Press.
Subspecies Three subspecies are widely recognized, although some authors prefer to regard them as distinct species. Polygonum oxyspermum subsp. oxyspermum – northern Europe; naturalized in Nova Scotia Polygonum oxyspermum subsp. raii (Bab.) D.A.Webb & Chater northern Europe; naturalized in Nova Scotia, Prince Edward Island, New Brunswick, Québec, Maine, Newfoundland Polygonum oxyspermum subsp. robertii (Loisel.) Akeroyd & D.A.Webb – ItalyActa Plantarum, Polygonum robertii Loisel. – Poligono di Robert
References
External links photos Flora of Northern Ireland