Man. Fl. Pl. Calif., 420. 1925.
Annuals; hirsute-hispid throughout. Stems unbranched or branched distally, 1.2–6 dm. Basal leaves not rosulate; shortly petiolate; blade lanceolate to oblanceolate, 2–8 cm, margins coarsely dentate to pinnatifid. Cauline leaves: blade lanceolate, 1.3–9 cm × 2–20 mm, (smaller distally), base auriculate, margins dentate. Racemes ebracteate, (lax, with a terminal cluster of dark purple or greenish yellow sterile flowers). Fruiting pedicels divaricate to ascending, (straight, curved upward, or recurved), 3–8 mm. Flowers: calyx campanulate; sepals (of fertile flowers) dark purple, purplish, or greenish yellow, (oblong to lanceolate), 4–6 mm, (8–14 mm in sterile flowers), not or slightly keeled, (hirsute-hispid in fertile flowers, glabrous in sterile flowers); petals: (abaxial pair spreading and reflexed, adaxial pair parallel and erect), purplish white, lemon-yellow, or yellowish white (with darker midvein), 7–12 mm, blade 2–4 × 1–2 mm, margins crisped, claw 5–8 mm, about as wide as blade; stamens in 3 unequal pairs; filaments: abaxial pair (distinct), 4–6 mm, lateral pair 3–4 mm, adaxial pair (connate their entire length), 6–9 mm; anthers: abaxial and lateral pairs fertile, 1.3–2 mm, adaxial pairs sterile, 0.2–0.7 mm; gynophore 0.4–1 mm. Fruits ascending or reflexed, smooth, straight or slightly curved, flattened, 3.5–11.4 cm × 1.5–2 mm; valves each with prominent midvein, (glabrate or sparsely to densely hispid, trichomes to 1.7 mm); replum straight; ovules 32–94 per ovary; style 1–2 mm; stigma entire. Seeds broadly oblong, 1.4–2 × 1–1.3 mm; wing 0.15–0.3 mm wide, continuous.
Subspecies 2 (2 in the flora).
|1||Racemes with terminal cluster of sterile flowers dark purple; sepals of fertile flowers dark purplish; petals purplish white; fruit valves usually glabrate or sparsely hispid, rarely densely so.||Streptanthus insignis subsp. insignis|
|1||Racemes with terminal cluster of sterile flowers greenish yellow or purple; sepals of fertile flowers greenish yellow or purplish; petals lemon-yellow or yellowish white; fruit valves moderately to densely hispid.||Streptanthus insignis subsp. lyonii|