Oenothera longissima
Long-stem evening-primrose, Long-Stem Evening-Primrose
(c) Stan Shebs, some rights reserved (CC BY-SA) · licence
Family: Onagraceae · Type: Herb · Native
Conservation status: CNPS 2B.2
Oenothera longissima (Long-stem evening-primrose) is a native California herb in the Onagraceae family, recognized by exceptional height and flower tube length diagnostic.
Long-stem evening-primrose is a rare (CNPS 2B.2) California native biennial found in the eastern desert mountains, specifically the New York Mountains, in seasonally moist creosote-bush scrub and pinyon/juniper woodland at elevations of 1,000 to 1,700 meters. Flowering from July to September, this plant produces bright yellow flowers that fade to red-orange, with large blossoms up to 6.5 centimeters long emerging from a distinctive spike. Growing with tall, erect stems reaching 6 to 30 decimeters in height, it develops with strigose hairs and characteristic red, bristle-like bases that give the plant a unique textural appearance. Its cauline leaves are narrowly oblanceolate to elliptic, measuring 5 to 22 centimeters long and ranging from nearly entire to slightly dentate. The fruit is a nearly cylindrical capsule 25 to 55 millimeters long, containing small, angled seeds with irregular pitting.
Identification and appearance
Key characters: 17 sympatric species; exceptional height and flower tube length diagnostic
Habitat and range
Habitat: Seasonally moist places in creosote-bush scrub, pinyon/juniper woodland
Elevation: 1000-1700 m
Outside California: to Colorado, Arizona
Bloom period
Oenothera longissima blooms Jul-Sep.
Conservation status
CNPS 2B.2
How to tell it apart
vs Camissoniopsis: Oenothera has a 4-lobed cross-shaped stigma; Camissoniopsis has a round stigma and four-angled fruits.; vs Clarkia: Oenothera has 4-lobed stigma and yellow flowers; Clarkia has round stigma and pink/purple flowers.; vs Rosa: Oenothera has 4 petals and capsule fruits; Rosa has 5+ petals and rose hips.; vs Convolvulus: Oenothera has separate petals; Convolvulus has fused trumpet-shaped flowers (morning glory family).; vs Taraxia: Oenothera has robust stems with 4-lobed stigma; Taraxia is stemless with flowers at ground level.
Frequently asked questions
Is Oenothera longissima native to California?
Yes. Oenothera longissima is native to California (recorded as native).
When does Oenothera longissima bloom?
Oenothera longissima blooms Jul-Sep.
What plant family does Oenothera longissima belong to?
Oenothera longissima is in the Onagraceae family, genus Oenothera.
Is Oenothera longissima rare or endangered?
Oenothera longissima carries California Rare Plant Rank 2B.2, state rank S1.
What habitat does Oenothera longissima grow in?
Oenothera longissima grows in Seasonally moist places in creosote-bush scrub, pinyon/juniper woodland.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.