There are a fair amount of changes within this genus, with plants being reclassified. Generally, perennials, sometimes weedy, with 4-petalled flowers, on a long pedicel or the flower forming a trumpet-shape.
Much-visited by bumblebees and wasps in search of sustenance, the flowers provide a resource to insects over an extended summer period. In addition, the leaves form the food plant of a number of moths, most notably the remarkable pink elephant hawk-moth.
With some sources Chamaenerion are still referred to as Epilobium.