Mesoreanthus vimineus Greene, Leafl. Bot. Observ. Crit. 1: 90. 1904; M. fallax Greene

Annuals; (glaucous), usually glabrous throughout (some-times sepals pubescent). Stems branched distal to base, 1-7.5 dm. Basal leaves (soon withered); not rosulate; petiolate; blade narrowly ovate to oblong, 2.5-5 cm, margins entire. Cauline leaves: blade linear to narrowly linear-lanceolate, 2-12 cm × 1-3(-4) mm, (smaller distally), base auriculate, margins entire. Racemes ebracteate, (lax, usually secund). Fruiting pedicels divaricate, (straight), 1-3(-6) mm. Flowers: calyx urceolate; sepals greenish to purplish, ovate-lanceolate, 6-8 mm, keeled, (apex recurved, usually glabrous, rarely sparsely pubescent); petals white (abaxial pair with purple veins), 8-12 mm, blade 3-5 × 2-3 mm, (unequal, abaxial longer than adaxial), margins not crisped, claw 5-7 mm, narrower than blade; stamens in 3 unequal pairs; filaments: abaxial pair (connate 1/2 their length), 4-7 mm, lateral pair 2-4 mm, adaxial pair (connate their whole length, recurved), 7-11 mm; anthers: abaxial and lateral pairs fertile, 2-2.7 mm, adaxial pairs sterile, 0.5-1.2 mm; gynophore 0.2-0.5 mm. Fruits divaricate, slightly torulose, recurved, flattened, 3.5-6.5 cm × 1-1.2 mm; valves each with obscure midvein; replum straight; ovules 28-40 per ovary; style 0.1-0.3 mm; stigma entire. Seeds narrowly oblong, 1-1.5 × 0.6-0.8 mm; wing 0-0.1 mm wide, distal.

Flowering May-Jul. Serpentine grasslands, ridges and barrens, openings in chaparral; of conservation concern; 200-800 m; Calif.

Streptanthus vimineus is restricted to Colusa, Lake, and Napa counties. The taxon has long been unrecognized by various authors, including recent ones (e.g., R. C. Rollins 1993; R. E. Buck et al. 1993). It remained under Mesoreanthus and was often treated as a synonym of S. barbiger. The latter always has non-auriculate (versus auriculate) cauline leaves.