Oenothera stricta subsp. stricta

Erect annual or biennial herb, to 1 m high; main stem simple or branched, lateral stems curved. Basal leaves rosetted, oblanceolate, 10–15 cm long, 3–10 mm wide, sessile, margins with widely spaced serrations or teeth, base often long-attenuate, midrib conspicuous; cauline leaves lanceolate, 3–8.5 cm long, 3–12 mm wide, sessile, margins shallowly toothed, upper leaves short and broad-based, bract-like. Flowers actinomorphic, opening near sunset and fading by morning, single, sessile, in upper leaf axils; hypanthium 2–4.5 cm long; sepals lanceolate, 15–19 mm long, often failing to separate completely, bent to one side; petals 1.5–3 cm long, yellow, sometimes red-based, becoming wine-red on ageing. Capsule more or less cylindric, broader in upper part, 3–4 cm long, 3–4 mm wide, sparsely villous, dehiscing mainly at apex.  Flowers mostly Aug.–Jan.