Herbs annual or biennial, densely to sparsely strigillose, glandular puberulent or some­times also sparsely villous distally. Stems unbranched or branched primarily distally, 25–70 cm. Leaves in a basal rosette and cauline, basal 6–12 × 0.7–2 cm, cauline 2–10 ×0.5–3 cm; subsessile; blade narrowly elliptic to oblanceolate, gradually narrowly lanceolate to lanceolate, elliptic, or ovate distally, margins lobed to remotely dentate or subentire; bracts shorter than capsule they subtend, 0.5–1.7 cm. Inflorescences open, lax, usually unbranched, mature buds usually over­topping spike apex. Flowers 1–few per spike opening per day near sunset; buds erect, with free tips erect, 1–3 mm; floral tube nearly straight, 20–40 mm; sepals 15–25 mm; petals yellow, broadly elliptic to rhombic-ovate, 20–30 mm; filaments 17–22 mm, anthers 4–7 mm, pollen 85–100% fertile; style 50–65 mm, stigma usually exserted beyond anthers at anthesis. Capsules narrowly lanceoloid, 15–33 × 2–3 mm. Seeds dark brown, ellipsoid, 1–1.4 ×0.4–0.6 mm. 2n = 14.

Flowering Apr–Jul. Sandy, open places in oak woodlands; 30–200 m; Tex.

Oenothera cordata is self-incompatible. It occurs in a narrow range in eastern Texas (Austin, Bastrop, Colorado, Fayette, Guadalupe, Goliad, Matagorda, San Patricio, Victoria, Waller, and Wilson). It apparently occasionally hybridizes with O. heterophylla subsp. heterophylla where their ranges come together.

Oenothera bifrons D. Don 1838 (not Lindley 1831) pertains here.