Down Garden Services


Common Knotgrass

Scientific Name: Polygonum aviculare
Other names: Birdgrass, Doorweed, Irongrass, Matgrass, Prostrate Knotweed, Stonegrass
Family: POLYGONACEAE(Buckwheat)

Annual, spreading by seed, it is not a grass as the common name might suggest, but is a member of the Polygonaceae Family. The wirey branched stems have 'knots' at leaf joints which are swollen with a covering silvery scale. The lance-shaped leaves have a short stalk. The sap can be irritant to the skin, but it has styptic properties and the crushed leaves have been used to staunch a nosebleed by rubbing into the nostrils.
Flowers from July to October - a cluster of small white flowers in the angle between leaf and stem.
Height - up to 60 cm, but on open ground it is usually prostrate, scrambling over the surface.

Hoe or hand pull, tough branching tap-root, giving rise to other name, Iron-grass. Applying mulch to newly cultivated bed should prevent germination.
In a newly sown lawn most of the topgrowth will be removed by the mower when cutting begins and as an annual it will die off later.

Weedkillers to use:-
Paraquat, Diquat kill on contact. Glyphosate will also work, but the delayed action may allow seeds to be shed if the plants are near maturity.

Follow these links for further details on Weeds, Weed Removal and Weed Prevention.

picture of Knotgrass