Oenothera drummondii Hook.

Herbs erect to procumbent, annual to perennial, usually without rosette, often with decumbent lateral branches terminating in a rosette. Stems 10-50 cm tall, stiff, simple or branched, densely strigillose, sometimes also villous, glandular puberulous on inflorescence. Leaves grayish green, with inconspicuous veins, densely strigillose, sometimes also glandular puberulous, sessile above, petioles 2-12 mm below; basal blade 5-14 × 1-2 cm; cauline blade narrowly oblanceolate or elliptic to broadly obovate, 1-8 × 0.5-2.5 cm, base attenuate, margin shallowly dentate to subentire, rarely lyrate, apex acute to rounded. Inflorescence a lax open spike. Flowers open near sunset, one per stem per day; floral tube 2.5-5 cm, upcurved in bud. Sepals 1.3-3.3 cm, with free tips 1-3 mm, apical, erect and appressed. Petals yellow, 2-4.5 cm. Anthers 4-12 mm; pollen 90%-100% fertile. Ovary densely strigillose to villous, sometimes also glandular puberulous; stigma exserted above anthers. Capsules cylindric, 2.5-5.5 cm, sessile. Seeds in two rows per locule, brown with darker flecks, ellipsoid to suborbicular, 1.1-1.7 mm, pitted. Fl. May-Nov, fr. Jun-Dec. 2n = 14; self-compatible, modally outcrossing.