Fibrous-rooted perennial to 1 m, simple or branched above, variously strigose or (especially upwards) spreading-hairy (but the hairs mostly shorter than in no. 15 [Oenothera pilosella Raf.]), or nearly glabrous below the infl, eglandular, or with only a few of the hairs gland-tipped; lvs narrowly elliptic to ovate or nearly linear, usually entire or nearly so, seldom over 6 cm; fls diurnal, out-crossing, several in a compact infl that only seldom nods at the tip; hypanthium 0.5–1.5 cm; sep (0.5–)1–2 cm, the tips short, usually free for only ca 1 mm or less; pet (1–)1.5–2.5 cm, notched at the summit; filaments 5–15 mm, alternately unequal; anthers 4–7 mm; style 12–18 mm; stigmas held above the anthers at anthesis; fr strongly tetragonal or narrowly 4-winged, evidently clavate or even obpyramidal, the body mostly 4–10 mm, tapering to a short or usually ± elongate pedicel-like base; 2n=28, 42, 56. Meadows, fields, and open woods, often in disturbed habitats; Mass. to Fla., w. to Ind., Mo., Okla., and La. June–Aug. (O. linearis; O. longipedicellata; Kneiffia allenii; K. f.)
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