Distribution: Occurring on both sides of the Cascades crest in Washington; widely distributed throughout much of North America.
Habitat: Meadows and stream banks, from the plains to the lower mountains, typically where disturbed.
Flowers: June-August
Origin: Introduced from Europe
Growth Duration: Biennial
Conservation Status: Not of concern
Pollination: Bees, moths
Grayish biennial or short-lived perennial, the stems 3-10 dm. tall, erect, simple or freely-branching, with short, appressed hairs and longer, spreading, reddish-based hairs.
Leaves alternate, the lower leaves petiolate, the upper sub-sessile, lanceolate, 1-2.5 cm. broad, entire to wavy-dentate.
Inflorescence an elongate spike, the buds erect, with bracts more or less the length of the capsules; calyx tube 3-5 cm. long, the 4 lobes 10-15 mm. long, reflexed, distinct; petals 4, yellow, 1-2 cm. long; stamens 8, equal to the petals and style; stigma with 4 linear lobes 4-7 mm. long; ovary inferior, 4-celled.
Capsule 2.5-4 cm. long, linear, cylindrical.
PNW Herbaria: Specimen records of Oenothera biennis in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Oenothera biennis checklist entry
OregonFlora: Oenothera biennis information
E-Flora BC: Oenothera biennis atlas page
CalPhotos: Oenothera biennis photos