Anogra albicaulis (Pursh) Britton; A. bradburiana Rydberg; A. buffumii A. Nelson; A. confusa Rickett; A. ctenophylla Wooton & Standley; A. perplexa Rydberg; Oenothera albicaulis var. xanthosperma H. Léveillé; O. ctenophylla (Wooton & Standley) Tidestrom; O. sinuata Linnaeus var. bicolor H. Léveillé

Herbs winter-annual, densely strigillose, also sparsely villous; from a taproot. Stems ascending to decumbent, 1–several from base, sometimes unbranched, erect or ascending, 5–30 cm. Leaves in a basal rosette and cauline, 1.5–10 × 0.3–2.5 cm; blade oblanceolate to oblong, margins subentire or coarsely dentate or pinnatifid. Flowers 1–3 opening per day near sunset; buds nodding, weakly quadrangular, without free tips; floral tube 15–30 mm, mouth glabrous; sepals 15–30 mm; petals white, fading pink, usually obcordate, sometimes obovate, (15–)20–35(–40) mm; filaments 11–17 mm, anthers 6–10 mm; style 25–50 mm, stigma exserted beyond anthers at anthesis. Capsules ascending to erect, usually straight, sometimes curved, cylindrical, weakly 4-angled, 20–40 × 3–4 mm, dehiscent 1/22n = 14.

Flowering (Feb–)Mar–Jun(–Dec). Dry, usually sandy flats and slopes; 1000–2300 m; Ariz., Colo., Idaho, Kans., Mont., Nebr., N.Mex., N.Dak., Okla., S.Dak., Tex., Utah, Wyo.; Mexico (Chihuahua, Sonora).

Oenothera albicaulis is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). Oenothera albicaulis has been reported from southern Nevada, but documentation is needed of its occurrence there.

Anogra pinnatifida Spach, Baumannia pinnatifida Spach, Oenothera pinnatifida Nuttall, O. purshiana Steudel, and O. purshii G. Don are illegitimate names that pertain here.