howellii O. drummondii O. elata O. elongata O. featherstonei O. flava O. fraserii O. fruticosa O. gaura O. glaucifolia O. glazioviana O. grandiflora O. grandis O. harringtonii O. hartwegii O. heterophylla O. hexandra O. howardii O. humifusa O. indecora O. jamesii O. laciniata O. lavandulifolia O. lindheimeri O. linifolia O. longissima O. longituba O. macrocarpa O. mendocinensis O. mexicana O. mollissima O. montevidensis O. nana O. nutans O. oakesiana O. odorata O. pallida O. parodiana O. parviflora O. pedunculifolia O. perennis O. peruana O. picensis O. pilosella O. primiveris O. pubescens O. punae O. ravenii O. rhombipetala O. rosea O. rubinervis O. sandiana O. santarii O. scabra O. serrulata O. siambonensis O. sinuosa O. speciosa O. stricta O. stubbei O. suffrutescens O. tafiensis O. tarijensis O. tetraptera O. triloba O. tubicula O. versicolor O. villaricae O. villosa O. wolfii O. xenogaura O. xylocarpa See: List of Oenothera species.

Oenothera caespitosa, a species of western North America, produces white flowers that turn pink with age.

Oenothera are used as food plants by the larvae of some Lepidoptera species, including the large white-lined sphinx (Hyles lineata).

In the wild, some species of evening primrose act as primary colonizers, quickly appearing in recently cleared areas.

They germinate in disturbed soils, and can be found in habitat types such as dunes, roadsides, railway embankments, and waste areas.

Based on observations of evening primroses (O. drummondii), a study discovered that within minutes of sensing the sound waves of nearby bee wings through flower petals, the concentration of the sugar in the plant's nectar was increased by an average of 20 percent.

[9][12] The pattern of repeated colonizations resulted in a unique genetic conformation in the Euoenothera whereby the chromosomes at meiosis can form circles rather than pairs.

Analysis of the cytology of these races and of artificial hybrids between them increased understanding of the genetic and geographic evolution of the Euoenothera.

[14][15] The appearance of sudden changes in Oenothera lamarckiana led the pioneering geneticist Hugo de Vries to propose what he called "mutation theory" in 1901 (Mutationstheorie in the German the original article was written in).

The understanding that the observed changes in hybrids of the plant were caused by chromosome duplications (polyploidy) rather than gene mutation did not come until much later.

Its etymology is uncertain, but it is believed to be derived from the Greek words οίνος θήρα (oinos thera) 'wine seeker'.

[21][23] Research indicates that orally-administered evening primrose oil does not relieve symptoms of premenstrual syndrome,[24][25] and does not have an effect on shortening the length of pregnancy or labor.