By September this straggling perennial catches the eye where it forms large patches in the undergrowth by streams and rivers.
It has large white flowers with petals divided nearly to the base, 5 styles, lower leaves with short (<1cm) petioles and its upper stems are glandular-hairy all round.
It resembles Greater Chickweed Stellaria neglecta
(which has stems with 1-2 lines of hairs between each internode and 3 styles) and the scarce Wood Chickweed S. nemorum
(which also has 3 styles, upper stems uniformly hairy and lower leaves with long (>2cm) petioles.