44. Oenothera hispida (Bentham) W. L. Wagner, Hoch & Zarucchi, PhytoKeys. 50: 26. 2015.
Gaura hispida Bentham, Pl. Hartw., 288. 1849; G. crispa (Spach) D. Dietrich; G. drummondii (Spach) Torrey & A. Gray; G. roemeriana Scheele 1848, not Oenothera roemeriana Scheele 1849; O. xenogaura W. L. Wagner & Hoch; Schizocarya crispa Spach 1839, not O. crispa Schultes 1809; S. drummondii Spach 1836, not O. drummondii Hooker 1834
Herbs perennial, spreading by rhizomes (forming colonies), strigillose, often also villous; from taproot. Stems ascending to decumbent, several-branched from base, usually also irregularly branched distally, sometimes with a single, unbranched stem, 20–60(–120) cm. Leaves in a basal rosette and cauline, 0.5–7.5(–9.5) × 0.1–2.2 cm, blade narrowly lanceolate to elliptic, margins subentire or shallowly sinuate-dentate. Flowers 4-merous, zygomorphic, opening near sunset; floral tube 4–14 mm; sepals 7–11(–14) mm; petals white, fading red, slightly unequal, elliptic, 6–10 mm, clawed; filaments 4–8.5 mm, anthers 3–6 mm, pollen 90–100% fertile; style 12–26 mm, stigma exserted beyond anthers at anthesis. Capsules erect, pyramidal in distal 1/2, conspicuously bulging at base of distal pyramidal part, strongly 4-angled, conspicuously bulging at base, abruptly constricted to terete proximal part, 7–13 × 3–5 mm; sessile. Seeds (2 or)3 or 4(–8), reddish brown, 2–2.5 × 1–1.3 mm. 2n = 28.
Flowering May–Jul(–Nov). Sandy loam; 60–1900 m; Ark., Calif., Ga., Tex.; c Mexico.
Oenothera hispida is native across the eastern half of Texas, south through Mexico to Oaxaca and Puebla; it is naturalized in Sevier County, Arkansas, coastal southern California, and Glynn County Georgia.
P. H. Raven and D. P. Gregory (1972[1973]) reported Oenothera hispida to be self-incompatible. It occasionally forms hybrids with O. suffrutescens.