Herbs densely villous, usually also glandular puberulent dis­tally. Stems usually erect, sometimes decumbent, slender, wiry, usually many-branched, to 50 cm. Leaves: proximalmost not clustered near base; blade linear to very narrowly elliptic, 0.8–3.5 × 0.1–0.3 cm, base cuneate or attenuate, margins sparsely serrulate, apex acute. Flowers opening near sunrise; floral tube 1.6–2.7 mm, usually moderately to very sparsely pubescent inside on proximal 1/2, rarely glabrous; sepals (3–)3.8–5.5 mm, reflexed in pairs; petals (4–)4.5–7 mm, each with 2 red dots basally; episepalous filaments 2.5–3.5 mm, epipetalous filaments 1.7–2.5 mm, anthers 0.8–1.3 mm, pollen with usually less than 10% of grains 4-pored; style (3.5–)4–7 mm, stigma surrounded by anthers at anthesis. Capsules 15–45 × 0.8–1.3 mm; subsessile. Seeds 0.6–0.8 × 0.3–0.4 mm. 2n = 28.

Flowering Mar–Aug. Open grasslands; 200–1600 m; Calif.

Camissonia lacustris is known from two disjunct areas: serpentine soil in Lake County and the Sierra Nevada foothills from El Dorado to Fresno counties.

P. H. Raven (1969) determined that Camissonia lacustris is a self-compatible tetraploid and autogamous; it is closely related to C. strigulosa.