Some species commonly escape from the garden. B. davidii in particular is a great coloniser of dry open ground; in towns in the United Kingdom, it often self-sows on waste ground or old masonry, where it grows into a dense thicket, and it is listed as an invasive species in many areas. It is frequently seen beside railway lines, on derelict factory sites and, in the aftermath of the Second World War, on urban bomb sites. This earned it the popular nickname of 'the bombsite plant' among people of the war-time generation.