An annual to short-lived perennial herb of waste ground, roadsides, disturbed pastures and arable land; also in a range of coastal habitats including drift-lines, shingle beaches, sand dunes, tidal river banks and the uppermost parts of saltmarshes. 0?845 m (Great Dun Fell, Westmorland).
There has been little change in distribution since the 1962 Atlas. Three subspecies occur in Britain: subsp. crispus occurs throughout the range of the species and subsp. littoreus and subsp. uliginosus are mapped separately.
Eurosiberian Southern-temperate element, but widely naturalised so that distribution is now Circumpolar Southern-temperate.