Polygonum aviculare can be distinguished from the other most common knotgrass species, polygonum arenastrum, by having leaves on side branches noticeably smaller than those on the main stem.
Main flower color:
All of the British Isles
Usually prostrate; stems are up to 100 cm long
Fields, waste ground, beach margins, verges
Five green tepals (sometimes red along the margins) and five petal-like lobes, pale pink to nearly white, fused at the base. Flowers are produced at the leaf nodes, solitary or in clusters of up to six
Ovate, hairless, sheathed at the base with silver-coloured stipules. Leaves on the main stem are around three times as long as those on the side branches
June to October