Sinapis alba L.

Annual taprooted herb. Stem erect, branching, bearing stiff reflexed hairs especially near base, or sometimes glabrous, 60–100 cm tall. Lvs glabrous or sparsely covered in coarse hairs, toothed. Lower lvs lyrate-pinnate, rarely 2-pinnatifid, 10–20 × 5–10 cm; terminal leaflet broadly ovate to triangular, shallowly to deeply 3-lobed, wider than rest of lf; lateral leaflets alternate, oblong to ovate, in (0)–1–4 pairs, the proximal ones usually shallowly toothed but rarely entire. Upper lvs petiolate, similar to lower but smaller, sometimes simple and 3-lobed. Racemes erect, to 40 cm long, glabrous or with sparse reflexed hairs. Pedicels patent to reflexed at fruiting, 10–20 mm long. Sepals ovate to obovate, glabrous, 3–6 × 1–1.5–(2) mm. Petals 7–11 × 3–5 mm. Silique (1)–3–6–(8)-seeded, ± constricted between the seeds, bearing bristly hairs especially on veins, rarely glabrous, 15–30 × 2–5 mm; beak strongly flattened, 0–1-seeded, = or > valves.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: (Jun.)–Oct.–Feb.; Fruiting: (Jun.)–Oct.–Feb.