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 < 1.5 m. Stem: prostrate to erect, glabrous, often glaucous, or puberulent (hairs long, spreading). Leaf: pinnately veined; petiole < 4 cm or 0; blade 1--10 cm, linear to elliptic or ovate, entire or shallow-toothed, glabrous or sparsely puberulent. Inflorescence: spike, raceme; bracts leaf-like; axis in bud straight or recurved at tip, in flower +- straight; buds erect or not. Flower: hypanthium obconic to cup-shaped, or long, slender, generally with ring of hairs within; sepals 4, generally fused to tip in bud, reflexed at least at base, staying fused at least at tip, in 4s or 2s, or all coming free; corolla bowl-shaped to rotate, petals 5--60 mm, often lobed or clawed, lavender or pink to dark red, pale yellow, or white, often spotted, flecked, or streaked with red, purple, or white; stamens 8, in 2 like or unlike series, or 4, filaments cylindric to wider distally, subtended by ciliate scales or generally not, anthers attached at base, pollen white or yellow to blue-gray, lavender, or +- red; ovary 4-chambered, glabrous or not, cylindric, fusiform, or wider distally, generally shallowly to deeply 4- or 8-grooved, stigma lobes 4, generally prominent. Fruit: generally capsule, elongate (short, indehiscent, nut-like). Seed: generally many, rarely 1--2, 0.5--2 mm, angled, crested or not, brown, gray, or mottled.
Etymology: (Captain William Clark, 1770--1838, of Lewis & Clark Expedition) Note: Self-fertile; self-pollinated or outcrossed; on herbarium specimens, curvature of inflorescence axis in bud generally reliable, pollen color generally not.
eFlora Treatment Author: Harlan Lewis
Reference: Lewis & Lewis 1955 Univ Calif Publ Bot 20:241--392

Stem: erect, < 9 dm; hairs 0 to dense. Leaf: petiole < 1 cm; blade 2--7 cm, linear to narrowly lanceolate. Inflorescence: axis in bud recurved at tip; buds pendent. Flower: hypanthium 1.5--10 mm; sepals staying fused in 4s; corolla bowl-shaped, petals obovate to fan-shaped, pink-lavender, often lighter toward base, spot 0 or 1 near middle or base, red; stamens 8, anthers alike; ovary 4- or rarely shallowly 8-grooved, puberulent. Fruit: 2.5--5 cm, generally wider distally; beak slender, < 10 mm. Chromosomes: n=14.
Note: From hybrids between Clarkia amoena and a probably extinct relative of Clarkia lassenensis.