Description from Flora of China
Herbs annual or biennial. Root stout, tuberlike, and napiform or fusiform, or branched and not tuberlike. Stem erect, ± branched, ribbed, striate. Basal leaves long petiolate; petiole stout, abaxially convex, adaxially flattened or slightly concave; leaf blade oblong, 20-30 × 10-15 cm, adaxially crisped, sublustrous, abaxially with strongly protruding veins, base cuneate, truncate, or slightly cordate, margin entire or undulate, apex obtuse. Cauline leaves alternate, smaller than basal ones; leaf blade ovate or lanceolate-oblong, base gradually narrowed into petiole, apex attenuate. Flowers 2- or 3-glomerulate. Perianth united at base; segments linear or narrowly oblong, becoming leathery and incurved in fruit. Utricle basally sunken into perianth, distally subsucculent. Seed red-brown, sublustrous, lenticular, 2-3 mm in diam.; perisperm farinaceous. Fl. May-Sep, fr. Jul.
This species is highly variable, with many subspecies, varieties, and forms described. Four cultivated varieties are here recognized in China.
Commonly cultivated. in China [native to N Africa, SW Asia, and Europe; widely cultivated].