Rosebay willowherb or fireweed

Chamaenerion angustifolium

''Chamaenerion angustifolium'', known in North America as fireweed, in some parts of Canada as great willowherb, and in Britain as rosebay willowherb, is a perennial herbaceous flowering plant in the willowherb family Onagraceae. It is also known by the synonyms ''Chamerion angustifolium'' and ''Epilobium angustifolium''. It is native throughout the temperate Northern Hemisphere, including large parts of the boreal forests.

This species has been placed in the genus ''Chamaenerion'' rather than ''Epilobium'' based on several morphological distinctions: spiral leaf arrangement; absence of a hypanthium; subequal stamens ; zygomorphic stamens and stigma. Under this taxonomic arrangement, ''Chamaenerion'' and ''Epilobium'' are monophyletic sister genera.

Two subspecies are recognized as valid:
* ''Chamaenerion angustifolium'' subsp. ''angustifolium''
* ''Chamaenerion angustifolium'' subsp. ''circumvagum'' Hoch