Description from Flora of China
Herbs biennial or perennial, rarely annual, (0.3-)0.6-1.5(-3) m tall, glabrous, glaucous. Stems erect or decumbent, branched at or above middle, sometimes fleshy at base. Basal and lowermost cauline leaves long petiolate, sometimes strongly overlapping and forming a head; petiole to 30 cm; leaf blade ovate, oblong, or lanceolate in outline, to 40 × 15 cm, margin entire, repand, or dentate, sometimes pinnatifid or pinnatisect and with a large terminal lobe and smaller, 1-13, oblong or ovate lateral lobes on each side of midvein. Upper cauline leaves sessile or subsessile in some cultivated forms, oblanceolate, ovate, or oblong, to 10 × 4 cm, base amplexicaul, auriculate, or rarely cuneate, margin entire, repand, or rarely dentate. Racemes sometimes fleshy and condensed into a head. Fruiting pedicels usually straight, ascending or divaricate, (0.8-)1.4-2.5(-4) cm. Sepals oblong, 0.8-1.5 cm × 1.5-2.7 mm, erect. Petals creamy yellow or rarely white, (1.5-)1.8-2.5(-3) × (0.6-)0.8-1.2 cm, ovate or elliptic, apex rounded; claw 0.7-1.5 cm. Filaments 0.8-1.2 cm; anthers oblong, 2.5-4 mm. Fruit linear, (2.5-)4-8(-10) cm × (2.5-)3-4(-5) mm, terete, sessile or on a gynophore to 3 mm, divaricate or ascending; valvular segment (2-)3-7.5(-9) cm, 10-20-seeded per locule, valves with a prominent midvein; terminal segment conical, (3-)4-10 mm, seedless or 1(or 2)-seeded; style obsolete. Seeds dark brown or blackish, globose, 1.5-2.5 mm in diam., minutely reticulate. Fl. Mar-Jun, fr. Apr-Jul. 2n = 18*.
Wild populations of var. oleracea are known only from the coastal cliffs of W Europe. Of the 15 varieties and 16 forms recognized by Helm (Kulturpflanze 11: 92-210. 1963), seven varieties are cultivated in China, the most commonly grown of which are vars. botrytis, capitata, gongylodes, and italica. The other varieties are less commonly grown.
Cultivated. Throughout China [native to W Europe; cultivated worldwide].