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Vascular Plants of California
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Oenothera

EVENING-PRIMROSE

Higher Taxonomy
Family: OnagraceaeView DescriptionDichotomous Key

Common Name: EVENING-PRIMROSE FAMILY
Habit: Annual to perennial herb (to tree). Leaf: cauline or basal, alternate, opposite, or whorled, generally simple and toothed (to pinnately compound); stipules 0 or generally deciduous. Inflorescence: spike, raceme, panicle, or flowers 1 in axils; bracted. Flower: generally bisexual, generally radial, often opening at either dawn or dusk; hypanthium generally prolonged beyond ovary (measured from ovary tip to sepal base); sepals 4(2--7); petals 4(2--7, rarely 0), often fading darker; stamens 2 × or = sepals in number, anthers 2-chambered, opening lengthwise, pollen interconnected by threads; ovary inferior, chambers generally as many as sepals (sometimes becoming 1), placentas axile or parietal, ovules 1--many per chamber, style 1, stigma 4-lobed (or lobes as many as sepals), club-shaped, spheric, or hemispheric. Fruit: capsule, loculicidal (sometimes berry or indehiscent and nut-like). Seed: sometimes winged or hair-tufted.
Genera In Family: 22 genera, +- 657 species: worldwide, especially western North America; many cultivated (Clarkia, Epilobium, Fuchsia, Oenothera). Note: Gaura moved to Oenothera. Fuchsia magellanica Lam. naturalized in northern California.
eFlora Treatment Author: Warren L. Wagner & Peter C. Hoch, family description, key to genera, treatment of genera by Warren L. Wagner, except as noted
Scientific Editor: Robert W. Patterson, Bruce G. Baldwin.
Oenothera
Habit: Annual to perennial herb, generally from taproot, occasionally rhizomed. Leaf: basal or cauline, alternate, generally pinnately toothed to lobed, generally sessile. Inflorescence: spike, raceme-like, or flowers in axils of distal, reduced leaves. Flower: radial or (sect. Gaura) bilateral, generally opening at dusk; sepals 4, reflexed in flower (sometimes 2--3 remaining adherent); petals 4, yellow, white, rose, or +- purple, generally fading +- orange to +- purple, tip notched or toothed; stamens 8, filaments sometimes (sect. Gaura) with paired teeth at base, anthers attached at middle; ovary chambers 4, stigma generally deeply lobed, generally > anthers and cross-pollinated (or +- = anthers and self-pollinated). Fruit: generally dehiscent, cylindric to ovoid or obovoid, cylindric to 4-winged or -angled, straight to curved, generally sessile (base sometimes seedless, stalk-like). Seed: in generally 2(1--3) rows per chamber, or clustered or reduced to 1--4 per fruit.
Species In Genus: 145 species: America, some widely naturalized. Etymology: (Greek: wine-scented)
Unabridged Note: Many species self-pollinated; some of these have chromosome peculiarities (ring of 14 in meiosis) and +- 50% pollen fertility; they yield genetically identical offspring.
Jepson eFlora Author: Warren L. Wagner
Reference: Wagner et al. 2007 Syst Bot Monogr 83:1--240
Unabridged Reference: Raven & Gregory 1972 Mem Torrey Bot Club 23:1--96; Dietrich & Wagner 1988 Syst Bot Monogr 24:1--91; Wagner 2005 Syst Bot 30(2):332--355
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Key to Oenothera

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Next taxon: Oenothera avita

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Citation for this treatment: Warren L. Wagner 2017, Oenothera, in Jepson Flora Project (eds.) Jepson eFlora, Revision 5, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=9766, accessed on January 23, 2025.

Citation for the whole project: Jepson Flora Project (eds.) 2025, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on January 23, 2025.