Oenothera cardiophylla Torrey var. petiolaris M. E. Jones

Herbs villous, sometimes also glandular puberulent. Flowers: floral tube 4.5–12 mm; petals 3–12 mm; style 8–23 mm, stigma often exserted beyond anthers at anthesis. 2n = 14.

Flowering Mar–May. Rocky walls, sandy alluvial flats, with Ambrosia dumosa, Hyptis emoryi, and Larrea tridentata; 0–700 m; Ariz., Calif.; Mexico (Baja California, Sonora).

Subspecies cardiophylla is known from southern San Bernardino County south to eastern San Diego County, California, and Yuma County (and possibly western Pinal County), Arizona, and south in northeastern and central Baja California, Mexico; it is also found on Isla Ángel de la Guarda, Isla San Esteban, Isla San Luis, Isla San Marcos, and Isla San Pedro Mártir in the Gulf of California. Isla San Esteban is the only locality for this subspecies in Sonora.