Oenothera deltoides var. howellii Munz, Aliso 2: 81. 1949

Herbs perennial, densely strigillose, also villous and glandular puberulent distally; with relatively long, fleshy roots, grayish. Stems erect or ascending, several from base, not thickened near base, with numerous shorter lateral branches, these not encircling stems in older plants, 40–80 cm. Leaves cauline, without clear basal rosette, at least at anthesis; blade lanceolate, margins runcinate-pinnatifid. Flowers: buds fluted in distal 1/2, with free tips 1–9 mm; sepals 20–30 mm; petals 20–40 mm. Capsules 45–60 × 3–4 mm. 2n = 14.

Flowering (Mar–)Jun–Jul(–Sep). Sand dunes and bluffs; of conservation concern; 0–30 m; Calif.

W. M. Klein (1964) determined subsp. howellii to be self-incompatible.

Subspecies howellii is known from the Antioch Dunes in Contra Costa County. Subspecies howellii is federally listed as endangered and is in the Center for Plant Conservation’s National Collection of Endangered Plants.