2. Streptanthus barbiger Greene, Pittonia 1: 217. 1888; Mesoreanthus barbiger (Greene) Greene, Leafl. Bot. Observ. Crit. 1: 89. 1904. TYPE: United States, California, Lake Co., Highland Springs, June 1888, A. B. Simonds s.n. (holotype, NDG!).

     Herbs, annual, glabrous throughout except sometimes for sepals, not mottled. Stems (0.7–)1–6.7(–8) dm, erect, branched above base. Basal leaves not rosulate, petiolate, soon withered, oblanceolate or oblong to lanceolate, 2–5(–7) x 0.5–1.5 cm, remotely dentate; middle cauline leaves linear to linear-lanceolate, (1.5–)3–9(–10) cm x 0.5–2 mm, sessile, not auriculate, entire; upper leaves similar, reduced. Racemes ebracteate, often secund, lax, without a terminal cluster for sterile flowers; fruiting pedicels ascending to divaricate, 1–2.5(–4) mm. Flowers: sepals forming urceolate calyx, green to purplish, ovate, 4–6 mm, slightly keeled, erect, recurved at apex, glabrous or hirsute with retrorse trichomes; petals white, 6–9 mm, not crisped, abaxial pair with purplish veins; blade 2–4 x 1.5–2.5 mm; claw 4–6 mm, narrower than blade; filaments in 3 pairs of unequal length; adaxial pair completely united, strongly recurved, purplish, 7–9 mm; abaxial pair united to about middle, 4.5–5.5 mm; lateral pair 2.5–3.5 mm; anthers of adaxial stamens sterile, 0.4–1 mm; anthers of abaxial and lateral stamens fertile, 1.5–2.2 mm. Fruits 2–6(–7) cm x 1.2–1.5 mm, divaricate-ascending to reflexed, slightly flattened, curved or rarely straight, slightly torulose; valves glabrous, with obscure midvein; gynophore 0.3–1 mm; replum straight; style 0.1–0.7 mm; stigma entire; ovules and seeds 22–38 per fruit. Seeds narrowly oblong, 1.3–1.8 x 0.6–0.8 mm, flattened; wing 0.1–0.25 mm wide distally, narrower or absent at margin, rarely seeds wingless. 2n = 28.

Flowering: May–Aug.

Habitat: serpentine ridges and barrens, openings in chaparral and cypress or pine-oak woodlands.

Elevation: 200–1500 m.

Distribution: United States (NC California).