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.

[2] It is also naturalized in eastern Canada and in the US State of Maine.

Flowers are green, white or pink,[5] in axillary clusters.

[6] Three subspecies are widely recognized, although some authors prefer to regard them as distinct species.