An erect annual of well-drained, open habitats such as pavements, waste places, walls, railway ballast and as a weed of cultivated ground. It is particularly characteristic of urban areas of S. and E. England. It also occurs occasionally on sand dunes and on sandy ground inland. Lowland.
This species has been known in the London area since 1690. It has shown a marked expansion of range in Britain since the 1962 Atlas, and was first recorded in Ireland in 1983.
Native of N. America; naturalised throughout Europe and in similar climatic regions almost worldwide.
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