Page author: David Giblin
Oenothera biennis

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.

Accepted Name:
Oenothera biennis L.
Publication: Sp. Pl. 1: 346. 1753.

Synonyms & Misapplications:
Oenothera biennis L. ssp. centralis Munz
Oenothera biennis L. var. pycnocarpa (Atk. & Bartlett) Wiegand
Oenothera muricata L.
Additional Resources:

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

6 photographs:
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