Stock stout with deeply descending taproot, up to ± 1·5 cm. diam., crowned by rosette of basal lvs. Radical lvs up to c. 5 cm. long, narrow linear-spathulate, subacute, narrowed into flat petiole, subcoriac., rather distantly and sharply toothed to subentire, glab. or with sparingly ciliate margins. Cauline lvs similar, smaller, uppermost subentire. Infl. up to 5 dm. or more long, much branched; fls ∞ in racemes; pedicels slender, up to 2 cm. long. Sepals c. 3 mm. long, oblong; petals white, c. 6 mm. long, spathulate, long-clawed. Siliques (1·5)-3-6 cm. × 4-6 mm., styles slender, c. 1-2 mm. long. Seeds c. 2 mm. long, broad-oblong in outline, compressed, reddish brown.