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Oenothera biennis  L.  subsp. centralis Munz
Atchison County, Kansas
Height: 20-80 inches
Family: Onagraceae - Evening-primrose Family
Flowering Period:   July, August, September,October
Stems: Erect, usually branched proximally or distally, short appressed hairy, often also with spreading, red-pustulate hairs; epidermis green, not exfoliating.
Leaves: Basal and cauline, alternate; basal leaves often withering before anthesis, petiolate, blade oblanceolate, 2.5 to 12 inches long, .4 to 2.8 inches wide, margins wavy-lobed, nearly entire or denticulate; cauline leaves sessile, blade lanceolate to elliptic, 1 to 6 inches long, .6 to 2 inches wide, margins denticulate to wavy, surfaces glabrous or canescent.
Inflorescences: Terminal spikes; bracts lanceolate, oblong, or ovate, .4 to 1.2 inch long.
Flowers: Radially symmetric; hypanthium .8 to 2 inches, glandular-puberulent and antrorsely puberulent; sepals 4, deciduous, absent on fruit, reflexed, linear-lanceolate, .4 to 1 inch, tips distinct or connate at anthesis; petals 4, yellow, fading orange or cream, obovate, .4 to 1 inch, apex slightly notched; stamens 8, anthers .25 to .28 inch; stigma positioned at about same level as anthers, deeply 4-lobed, lobes .12 to .25 inch.
Fruits: Capsules, dehiscent, ascending or erect, lanceoloid, .6 to 1.6 inches long, .14 to .25 inch wide, straight, not winged, strigose to nearly glabrous. Seeds many per fruit, reddish brown, irregularly prismatic and angled, .05 to .06 inch, irregularly ridged and pitted, without coma.
Habitat: Pastures, roadsides, open woodlands, shores of ponds and lakes, disturbed sites.
Distribution: Principally the east third of Kansas
Origin: Native
Uses: Native Americans used the seeds for food, cooked and ate the leaves as greens, boiled the roots like potatoes, and soaked the plant and applied it as a poultice to bruises (Moerman 1998).
Comments: Oenothera, a name used by Theophrastus for a species of Epilobium. Oenothera biennis is quite similar to Oeonothera villosa but is greener in color, bears some glandular hairs in the inflorescence, and has thinner leaves than that species.

Common evening-primrose inflorescence
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Atchison County, Kansas
Common evening-primrose leaves
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Atchison County, Kansas
Common evening-primrose fruit
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Atchison County, Kansas
Common evening-primrose stem pubescence
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Atchison County, Kansas
Common evening-primrose leaves and fruit
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Atchison County, Kansas
Common evening-primrose flowers
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Atchison County, Kansas
Common evening-primrose
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Atchison Coiunty, Kansas