Oenothera heterophylla Spach var. curtissii (Small) Fosberg

Herbs biennial or short-lived perennial, densely to sparsely strigillose, sometimes also sparsely glandular puberulent distally. Stems sometimes with lateral branches arising obliquely from rosette, 30–80 cm. Leaves in a basal rosette and cauline, basal 7–17 × 0.5–1.5 cm, cauline 2–8 × 0.5–1.5 cm; blade narrowly oblanceolate, gradually narrowly elliptic to narrowly oblong distally, margins lobed to remotely dentate or subentire; bracts slightly longer than capsule they subtend. Inflorescences open, lax, without lateral branches, mature buds usually not overtopping spike apex. Flowers 1 or 2 per spike opening per day near sunset; buds erect, with free tips erect to spreading, 0.3–0.8 mm; floral tube slightly curved upward to straight, 23–37 mm; sepals 7–13 mm; petals yellow, broadly elliptic to rhombic-ovate, 8–17 mm; filaments 6–10 mm, anthers 1.5–4 mm, pollen ca. 50% fertile; style 30–45 mm, stigma surrounded by anthers at anthesis. Capsules narrowly lanceoloid, 10–25 ×2–3 mm. Seeds brown, sometimes flecked with dark red spots, ellipsoid, 1–1.3 × 0.5–0.7 mm. 2n = 14.

Flowering Jun–Sep. Dry places, pine-oak woods, fields, roadsides, sandy soil; 0–60 m; Ala., Fla., Ga., S.C.

Oenothera curtissii is a PTH species and forms a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous (W. Dietrich and W. L. Wagner 1988). It is known only from northern Florida, adjacent southern Georgia and southeastern Alabama, and one disjunct locality in South Carolina (Allendale County).