Chamerion angustifolium Rosebay Willowherb

A tall perennial which grows on disturbed ground, often after burning. With its spires of attractive pink-purple flowers it is familiar to most people. Less often, white-flowered populations are encountered (see photo). Rosebay is a very common, ubiquitous species in Britain with records from virtually all the hectads in Britain and Ireland. However, in the 19th century and for much of the first half of the 20th century it was a relatively uncommon species of rocky places. The extraordinary range expansion which took place after the Second World War is often related to its opportunistic colonisation of bombed sites in London followed by dispersal along the railway network to all parts of the country. However the plants that became so familiar in London at that time may have been introduced from overseas with a genetic make-up that allowed them to expand the range of the species in Britain in the decades that followed the war. It produces typical willowherb seed pods which liberate huge amounts of plumed seeds that are dispersed effectively and for long distances by the wind. In West Glamorgan it is a plant mostly of disturbed sites, ruderal habitats, roadsides and railways. It is often abundant in clear-felled coupes in conifer plantations where its vigorous rhizomatous growth allow it to form dense stands in the early successional stages.

Although Rosebay is a native species in the British flora, the extent to which our populations include plants of native provenance is unclear.