Oenothera palmeri S. Watson, Proc. Amer. Acad. Arts 12: 251. 1877; Camissonia palmeri (S. Watson) P. H. Raven; Taraxia palmeri (S. Watson) Small

Herbs sparsely to moderately strigose and sometimes also sparsely pilose. Stems rarely present, swollen, ascending to 2 cm. Leaves: blade narrowly oblanceolate, 1.5–5.5 × 0.2–0.7 cm, dilated at base, margins sparsely and evenly serrulate. Flowers opening near sunrise; floral tube 0.8–1.3 mm; sepals 1.6–2.8 mm; petals 2–5 mm; episepalous filaments 0.8–1 mm, epipetalous filaments 0.2 mm; sterile projection of ovary 5.5–12 mm; style 1–2.2 mm, glabrous; stigma 0.3–0.6 mm diam., surrounded by anthers of long and short stamens. Capsules irregularly obovoid, thick-walled, somewhat woody, sharply 4-angled, with pointed wing near center-top of each valve, 5–7 × 4.5–7 mm, tardily dehiscent in distal 1/2 only. Seeds brown, narrowly obovoid, 1.2–2 mm. 2n = 14.

Flowering Mar–May. Desert habitats, on clay or sandy soil, creosote to sagebrush-juniper woodlands; 600–1400 m; Ariz., Calif., Nev., Oreg.

Tetrapteron palmeri has a disjunct distribution, occurring in four distinct areas: Arizona, represented only by the type specimens collected in the Colorado River valley in 1876; near Harper and Vale, Malheur County, Oregon; north of Winnemucca, Humboldt County, and Empire City, Ormsby County, Nevada; in California it is fairly common from southern Inyo County to the southwestern border of the Mojave Desert, west to the vicinity of Tejon Pass and south­eastern San Luis Obispo County in the inner South Coast Ranges, and also east of Jacumba on the road to Moun­tain Springs in San Diego County.