TheOnagraceae are afamily offlowering plants known as thewillowherb family orevening primrose family. They include about 650 species ofherbs,shrubs, andtrees[4] in 17 genera.[5] The family is widespread, occurring on every continent fromboreal totropical regions.
The family includes a number of populargarden plants, including evening primroses (Oenothera) andfuchsias (Fuchsia). Some, particularly the willowherbs (Epilobium), are commonweeds in gardens and rapidly colonize disturbed habitats in the wild. One such species isfireweed (Chamaenerion angustifolium).
The family is characterised byflowers with usually foursepals andpetals; in some genera, such asFuchsia, the sepals are as brightly coloured as the petals.
Theseeds are generally very small. In some genera, such asEpilobium, they have tufts of hairs[6] and aredispersed on the wind. In others, such asFuchsia, the seeds develop in juicyberries dispersed by animals. Theleaves are commonly opposite or whorled, but are spirally arranged in some species; in most, they are simple and lanceolate in shape. Thepollen grains in many genera are loosely held together byviscin threads. Mostbees cannot collect it, and only bees with specialized morphologies can effectively pollinate the flowers; nearly all bee taxa that visit the flowers areoligoleges specialized on the family Onagraceae.
The family was named after the genusOnagra (now known asOenothera) in 1836 byJohn Lindley in the second edition ofA Natural System of Botany.
Several genera are synonymized but appear often in older literature as belonging to the previous genera. For exampleCalylophus andGaura, which have both been absorbed intoOenothera.[15] LikewiseEucharidium is a synonym ofClarkia.[16]
