Chamaenerion

Chamaenerion is a genus of flowering plants in the family Onagraceae (the evening primrose or willowherb family). It has sometimes been included in the genus Epilobium. Members of the genus may be called willowherbs (along with Epilobium), or fireweeds, based on a common name used for C. angustifolium. They are upright herbaceous perennials, growing from a woody base or from rhizomes, with racemes of usually purple to pink flowers. All species are found in the northern hemisphere. Most occur in moist habitats; C. angustifolium is the exception, favouring disturbed ground.

==Description== Chamaenerion species are upright herbaceous perennials with either unbranched stems or, much less often, slightly branched stems. They either have a woody base or grow from rhizomes. The leaves are generally spirally arranged on the stems and are usually narrow, rarely ovate. The inflorescence is a simple or slightly branched raceme. Individual flowers have four petals that are rose-purple to pink, rarely white. The petals are free at the base rather than united in a floral tube, as in Epilobium. The lower petals are narrower than the upper ones, making the flower radially unsymmetric (zygomorphic). There are eight more-or-less equally sized stamens, and a long, four-lobed style. The fruit is a long, thin, four-chambered (loculicidal) capsule that splits to reveal the many seeds. The seeds have a tuft of hairs at one end.