Oenothera albicaulis Nuttall, Gen. N. Amer. Pl. 1: 245. 1818, not Pursh 1813; O. albicaulis Pursh var. nuttallii (Sweet) Engelmann

Herbs perennial, mostly gla­brous, sometimes strigillose on leaves and/or glandular puberulent on distal parts, at least on floral tube; from a taproot, lateral roots producing adventitious shoots. Stems erect, often branched, 30–100 cm. Leaves in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, 2–6(–10.5) × 0.3–0.6(–1) cm; petiole 0–2 cm; blade narrowly oblong to oblong-lanceolate, margins usually entire, sometimes remotely denticulate or repand-denticulate. Flowers 1–several opening per day near sunset; buds nodding, weakly quadrangular, with free tips 1–2 mm; floral tube 15–40 mm; sepals 20–30 mm, not spotted; petals white, fading pink, broadly obovate or obcordate,15–30 mm; filaments 15–18 mm, anthers 8–10 mm; style 35–45 mm, stigma exserted beyond anthers at anthesis. Capsules erect or ascending, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering slightly from base to apex, 20–30 × 2–3 mm; sessile. Seeds numer­ous, in 1 row per locule, reddish dark brown, narrowly obo­void, 1.5–2.3 mm. 2n = 14, 28.

Flowering Jun–Sep. Dry, sandy or rocky prairies, open wooded hillsides, disturbed areas, roadsides; 500–2200(–2900) m; Alta., Man., Sask.; Colo., Ill., Mich., Minn., Mont., Nebr., N.Dak., S.Dak., Wis., Wyo.

Oenothera nuttallii had been assumed to be self-incompatible (W. L. Wagner et al. 2007), but K. E. Theiss et al. (2010) determined two plants to be self-compatible.

Anogra nuttalliana Spach and Baumannia nuttalliana Spach are illegitimate names that pertain here.