Oenothera laciniata Hill var. mexicana (Spach) Small; O. sinuata Linnaeus var. hirsuta Torrey & A. Gray; Raimannia mexicana (Spach) Wooton & Standley

Herbs annual, moderately to sparsely strigillose and densely long-villous, sometimes also becoming glandular puberulent distally. Stems erect to ascending, usually unbranched, or with arcuate lateral branches arising from rosette, 15–40(–60) cm. Leaves in a basal rosette and cauline, basal 6–10 × 1–2.5 cm, cauline 3–7.5 × 0.8–2 cm; blade usually grayish green, narrowly oblanceolate to narrowly oblanceolate, margins deeply lobed, lobes usually dentate; bracts distalmost erect, revolute. Flowers usually 1 opening per day near sunset; buds erect, with free tips erect or appressed, 0.5–2.5 mm; floral tube 23–28 mm; sepals 5–12 mm; petals yellow, fading orange, broadly obovate or shallowly obcordate, 6–15 mm; filaments 4–12 mm, anthers 3–4 mm, pollen 85–100% fertile; style 27–40 mm, stigma surrounded by anthers at anthesis. Capsules cylindrical, sometimes slightly enlarged toward apex, 25–45 × 2.5–3 mm. Seeds ellipsoid to subglobose, 0.8–1.2 × 0.3–0.5 mm. 2n = 14.

Flowering Apr–May. Open, sandy sites; 30–200 m; Tex.

Oenothera mexicana is known only from southeastern Texas (Atascosa, Aransas, Bexar, Brooks, Burleson, De Witt, Frio, Gonzales, Kenedy, Medina, Newton, Refugio, San Patricio, Waller, and Washington counties). It is self-compatible and autogamous, but not a PTH species.