Oenothera claviformis Torrey & Frémont var. peirsonii Munz, Amer. J. Bot. 15: 238. 1928 (as clavaeformis); Camissonia claviformis (Torrey & Frémont) P. H. Raven subsp. peirsonii (Munz) P. H. Raven; Chylismia peirsonii (Munz) D. A. Johansen; O. claviformis subsp. peirsonii (Munz) P. H. Raven

Herbs villous, at least proximally, rarely strigillose or glandular puberulent. Stems 5–60 cm. Leaves: blade lateral lobes usually well developed, terminal lobe narrowly ovate, to 9 × 3.5 cm, margins irregularly sinuate-dentate. Flowers opening at sunset; buds with conspicuous, subapical free tips; floral tube orange-brown inside, 2.5–4.5 mm; petals usually yellow, rarely white, not changing color in fading, 4.5–7 mm. 2n = 14.

Flowering Feb–Apr. Sandy flats or washes, with Ambrosia dumosa, Fouquieria splendens, and Larrea; -70–400 m; Calif.; Mexico (Baja California).

Subspecies peirsonii is known from east of the Salton Sea and Imperial Valley in Imperial and San Diego counties, California, and in northeastern Baja California to the Gulf of California. It intergrades with subsp. aurantiaca.