Chamerion angustifolium (L.) Holub
Plant height 80-150 cm. Flower 20-30 mm long.
Also called Fireweed after it grew on bombsites during World War I and World War II, this native perennial can grow in extensive clumps with its spreading rhizome root system. The showy pink flowers grow on tall pyramidal spikes. The leaves are narrow and pointed, and slightly toothed.
It flowers June to September and is seen in various habitats, including field margins, woodland clearings, riverbanks, brownfield sites, railway embankments and roadside verges. Common and widespread throughout most of Britain, less so further north.