Lavauxia brachycarpa (A. Gray) Britton; L. graminifolia (H. Léveillé) Rose; L. wrightii (A. Gray) Small; Megapterium brachycarpum (A. Gray) Rydberg; M. brachycarpum var. wrightii (A. Gray) Moldenke; Oenothera australis (Wooton & Standley) Tidestrom; O. brachycarpa var. wrightii (A. Gray) H. Léveillé; O. cespitosa Nuttall subsp. australis (Wooton & Standley) Munz; O. cespitosa var. australis (Wooton & Standley) Munz; O. graminifolia H. Léveillé; O. wrightii A. Gray; Pachylophus australis Wooton & Standley

Herbs acaulescent or sometimes caulescent, strigillose, also hirsute, hairs often with reddish purple pustulate base, glandular puberulent distally; from a woody taproot, sometimes lateral roots producing adventitious shoots. Stems (when present) ascending, longer ones becoming decumbent, usually densely leafy, 0–20(–36) cm. Leaves in a basal rosette, sometimes also cauline, (3.1–)5–21(–34) × (0.3–)1.5–3.5(–5.3) cm; petiole (0.8–)2.5–11(–15) cm; blade usually lanceolate to elliptic, rhombic-obovate, sometimes suborbicular or linear, usually irregularly pinnatifid, some sinuses extending nearly to midrib, usually with a large terminal lobe (0.1–)1.5–2(–2.4) cm, margins erose, apex acute to obtuse or rounded. Flowers usually 1–3, rarely more, opening per day near sunset, weakly scented; buds with unequal free tips 1–7 mm; floral tube (90–)120–210(–220) mm; sepals 38–55 mm; petals pale yellow to yellow, fading pale orange to pink, drying lavender to purple, usually broadly rhombic-obovate, sometimes obovate, (38–)45–58(–62) mm, distal margin usually erose; filaments (16–)20–32 mm, anthers (8–)13–21 mm; style (123–)155–240(–255) mm, stigma exserted beyond anthers at anthesis. Capsules leathery or corky, ovoid to narrowly ellipsoid, ± winged, wings 0–3(–5) mm wide, sometimes capsule with corky thickening between wings, then capsule only 4-angled, body (12–)18–40 × 6–10 mm, dehiscent 1/4 their length; pedicel 0–3 mm. Seeds usually numerous, in 1 or 2 rows per locule, obovoid to subcuboid, 3–5 × 1.8–2.2 mm. 2n = 14.

Flowering Mar–Aug. Rocky sites, usually on limestone, shale, or gypsum, on igneous substrates from canyons and slopes in Chihuahuan Desert scrub, grasslands, oak-pine-juniper woodlands, open sites in ponderosa pine-Douglas fir forests; 1000–2700 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Durango, Sonora).

Oenothera brachycarpa occurs from southeastern Arizona in southern Navajo, southeastern Pima, Graham, Santa Cruz, and Cochise counties, east across southern New Mexico to Val Verde and Pecos counties in trans-Pecos Texas.