Oenothera heterochroma S. Watson, Proc. Amer. Acad. Arts 17: 373. 1882; Camissonia heterochroma (S. Watson) P. H. Raven; C. heterochroma var. monoensis (Munz) Cronquist; O. heterochroma subsp. monoensis (Munz) P. H. Raven; O. heterochroma var. monoensis Munz

Herbs annual, glandular puberulent throughout, or glabrate and glaucous distally. Stems several, 10–100 cm. Leaves primarily in poorly defined basal rosette, cauline greatly reduced when present; petiole 0.4–8 cm; blade unlobed, ovate to cordate, 2–11.5 × 1.4–5 cm, margins sinuate-dentate, brown oil cells prominently lining veins abaxially. Racemes erect, elongating in anthesis. Flowers opening at sunrise; buds without free tips; floral tube 2–5 mm, villous inside; sepals 1.5–3.5 mm; petals lavender, paler and often with flecks toward base, often yellow at very base, fading darker lavender, 2–6 mm; stamens unequal, filaments of antisepalous ones 1.8–3 mm, of antipetalous ones 1–2.5 mm, anthers 0.6–1 mm, glabrous or sparsely ciliate; style 4–7 mm, stigma surrounded by anthers at anthesis. Capsules erect, clavate, 7–13 mm; pedicel 2–5 mm. Seeds 1–1.2 mm. 2n = 14.

Flowering May–Jun. Alluvial and rocky slopes; 600–2200 m; Calif., Nev.

Chylismia heterochroma is known from Churchill and Lander counties, Nevada, south to Lincoln and southern Nye counties, Nevada, to adjacent California (Mono Lake, Mono County, and central Inyo counties). P. H. Raven (1962, 1969) determined this species to be self-compatible and autogamous.