in N. L. Britton et al., N. Amer. Fl. 25: 86. 1907.
Herbs, (10–)20–40(–50) cm, glabrous or glabrate; branches from distal stem nodes, alternate, virgate (proximal unbranched main axis long in comparison to distal portion). Leaves alternate; stipular glands present; blade threadlike to linear, 10–25 × 1–1.5(–2) mm, base flat, not clasping, margins eglandular. Inflorescences: cymes monochasial, dense, sparingly branched, internodes short and flowers condensed or internodes long near base and flowers condensed at apices; bract margins eglandular. Pedicels 0.5–2(–5) mm, to 10 mm in fruit, ascending, not bent at apex. Flowers: sepals erect, lanceolate to narrowly ovate, 3.5–4 mm, subequal, margins minutely glandular-toothed, surfaces glabrous; petals widely spreading, white or partly pink, irregularly veined or flushed with pink or rose pink, obovate, (4–)6–8(–12) mm, apex obtuse, slightly erose; cup white, rim with petal attachments set in deep notches; stamens exserted; filaments (4–)5–7(–8) mm; anthers white to rose, dehisced anthers 2(–3) mm; ovary chambers 6; styles 3, white, (4–)5–7(–10) mm, exserted. 2n = 36.
Phenology: Flowering Apr–Jul.
Habitat: Rocky areas, chaparral, grassland, usually on serpentine soils.
Elevation: 30–1300 m.
Hesperolinon californicum usually occurs on serpentine soil in the central Inner Coast Ranges and on nonserpentine soil in the foothills east and west of the Sacramento Valley and west of the San Joaquin Valley.