Knotgrass, Ray's

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