Stems erect, 30–80 cm high, herbaceous, simple or branched, bristly or glabrous. Leaves petiolate, to 15 cm long (upper leaves smaller), pinnate to pinnately-lobed, terminal lobe elliptic to lanceolate, irregularly toothed, usually bristly, upper leaves smaller. Sepals spreading or reflexed, 4–6 mm long; petals usually 10–12 mm long. Fruit spreading, 2–4 cm long (including beak), 3–4 mm wide, cylindric to flattened at both ends; valves more or less constricted between seeds, bristly; beak 10–30 mm long, thick and flattened, sabre-like, with 0 or 1 seed; pedicel 5–15 mm long; seeds 1–2 mm wide, pale brown. Flowers Nov.–Jan.
LoM, VVP, EGU, HSF. Native to Mediterranean through to Russia. Occasional crop-weed.
In Europe, Sinapis alba subsp. albahas been used as a green salad (mustard and cress) but is now largely replaced for this purpose by Brassica ×napus. Seeds are mixed with those of B. ×juncea(rarely B. nigra) to make commercial mustard.
