Polygonum oxyspermum

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

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 100 cm long. Leaves are up to 35 mm long. Flowers are green, white or pink, in axillary clusters.

Three subspecies are widely recognized, although some authors prefer to regard them as distinct species.
 * Subspecies
 * 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 – Italy