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.
Phenology: Flowering Mar–Jun.
Habitat: Roadsides, disturbed areas, waste grounds, fields
Elevation: 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.