Oenothera missourensis Sims var. incana A. Gray, Boston J. Nat. Hist. 6: 189. 1850; Megapterium argyrophyllum R. R. Gates; O. macrocarpa var. incana (A. Gray) Reveal

Herbs strigillose, usually densely so, rarely glabrous, and sometimes glandular puber­ulent distally. Stems several, unbranched, sometimes with shorter secondary branches, 1–20(–30) cm. Leaves usually gray, rarely green, (5–)6.2–12.5(–17) ×2–4.3 cm; blade usually very broadly elliptic to suborbiculate, rarely oblanceolate or elliptic, margins usually flat, sometimes undulate, usually entire, sometimes inconspicuously denticulate, apex usually acute to obtuse, sometimes retuse. Flowers: buds with unequal free tips 5–11 mm; floral tube (50–)70–140(–160) mm; sepals (25–)35–50 mm; petals (25–)31–50(–52) mm; filaments (13–)15–25(–28) mm, anthers(10–)14–20 mm; style (75–)100–192 mm. Capsules broadly ellipsoid to globose, not twisted, wings 10–15(–24) mm wide, body 28–48(–74) × 6–8 mm. 2n = 14.

Flowering Apr–Jun(–Aug). Rocky, clay soil, grass­lands, disturbed sites, limestone, gypsum, rarely igneous soil; (500–)600–1200 m; Kans., Okla., Tex.

Subspecies incana occurs on the high plains in Clark, Comanche, Kiowa, and Meade counties, Kansas, south across Oklahoma as far east as Comanche and Harper counties to the Texas Panhandle to Garza and Knox counties; one collection is known from Taylor County, Texas.