Oenothera acaulis

Perennial herb; stems procumbent, to c. 40 cm long, with dense short hairs. Basal leaves rosetted, oblanceolate, 5–20 cm long, 6–60 mm wide, pinnatifid to lyrate, petiolate; cauline leaves similar to basal leaves, but generally smaller. Flowers single, in leaf axils, actinomorphic, opening near sunset and fading by morning; hypanthium 10–11 mm long, cylindrical to clavate; sepals linear-lanceolate, 25–30 mm long, often failing to separate completely, bent to one side; petals 15–35 mm long, white, fading to pink. Capsule obovoid, c. 10–20 mm long, c. 7 mm wide, covered with fine spreading hairs, 4-winged, wings c. 2–7 mm wide. Flowers Oct.–Nov.