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.

Habit: Annual from taproot. Leaf: basal and/or cauline, alternate, simple to 2-pinnate. Inflorescence: spike. Flower: opening at dusk; sepals 4, reflexed singly or in pairs; petals 4, generally white, pink, or rarely red, without spots or ultraviolet reflective area, fading red; longer stamens opposite sepals, anthers attached at middle, pollen grains 3-angled; stigma hemispheric, generally > anthers and cross-pollinated or +- = anthers and self-pollinated. Fruit: straight to coiled, sessile. Seed: in 1 row per chamber, obovoid to oblanceoloid, minutely pitted, sometimes those near base of fruit coarsely papillate.
Etymology: (Greek: desert + Oenothera) Note: Incl in Camissonia in TJM (1993).
eFlora Treatment Author: Warren L. Wagner
Reference: [Wagner et al. 2007 Syst Bot Monogr 83:1--240]
Unabridged Reference: Raven 1969 Contr US Natl Herb 37:161--396