This is a European introduction and garden escape which is sometimes naturalised on waste ground and seems able to compete even with some of more vigorous native species like Rosebay Willowherb. It is fairly common naturalised in southern England but much rarer elsewhere (including this site in north western England) and is absent from Ireland.

Waste ground at the side of East Lancs. road near St. Helens 18th July 2005

Added on 19th December 2005, updated 19th February 2012