Cheiranthus longipetalus Ventenat, Descr. Pl. Nouv., plate 93. 1802; C. bicornis Sibthorp & Smith; Matthiola bicornis (Sibthorp & Smith) de Candolle; M. longipetala subsp. bicornis (Sibthorp & Smith) P. W. Ball

Annuals; sparsely to moderately pubescent, (glandular papillae present or not). Stems erect or ascending to decumbent, (1-)1.5-5(-6) dm, pubescent, (glandular or not). Basal leaves not forming vegetative rosettes. Cauline leaves: petiole to 2 cm or (distal) sessile; blade linear-lanceolate to lanceolate or oblanceolate, (2-)3.5-8(-11) cm × 2-10(-20) mm (smaller distally), base attenuate to cuneate, margins usually pinnatisect to sinuate or dentate, rarely entire or subentire. Fruiting pedicels divaricate to divaricate-ascending, straight, (0.5-) 1-2(-3) mm, nearly as thick as fruit. Flowers: sepals narrowly oblong, (7-)8-11(-12.5) × 1-2 mm; petals usually purple, pink, yellow, or brown, rarely white, oblong to linear-lanceolate, (15-)18-23(-27) × 2-4(-5) mm, claw 7-13 mm, (margin crisped), apex subacute to obtuse; filaments 4-6 mm; anthers 2.5-3.5 mm. Fruits ascending to divaricate or, rarely, descending, straight, terete, (2.5-)4-8.5(-10) cm × 1-2 mm; valves pubescent, (often glandular); style obsolete to 3 mm; stigma horns 2, straight or curved upward, sometimes reflexed, 2-8 (-12) mm. Seeds suborbicular to oblong or ovate, 1-2 × 0.8-1.2 mm; wing 0.1-0.2 mm. 2n = 14.

Flowering Mar-Jun. Roadsides, disturbed areas, waste grounds, fields; 700-1300 m; introduced; Alta., Ont., Sask.; Ariz., Calif., Tex.; Europe; c, w Asia; n Africa; introduced also in Australia.

Matthiola longipetala is sporadically naturalized in North America and Australia.