Information on Ray's Knotgrass

Common Name: Ray's Knotgrass
Scientific Name: Polygonum oxyspermum
Irish Name: Glúineach ghlé
Family Group: Polygonaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Ray's Knotgrass could sometimes be confused with:

Knotgrass, Knotgrass, Equal-leaved,

This is a prostrate, native annual plant. It has 3mm, pinkish-white, 5-lobed flowers which are borne in clusters of 2-6 in leaf axils along ridged, sprawling stems. It can spread to 100cm long. The leaves are alternate, oval, leathery, grey-green with the margins slightly downturned. Nut-like fruits protrude beyond withering flowers, unlike Knotgrass or Equal-leaved Knotgrass. Its habitat is usually undisturbed, sandy beaches, shingle at extreme high-tide level. It belongs to the Dock family. 

I first saw this plant at Lady's Island Lake in Co Wexford in 2012 when it was pointed out to me by the BSBI Vice-county Recorder for Wexford and Waterford, Paul Green. 

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Knotgrass, Ray's
Knotgrass, Ray's