A tall, biennial herb, 40-100 cm tall, sparsely branched above, erect, leafy with cauline leaves not amplexicaul, large, dentate. Racemes 20-30-flowered, up to 20 cm long in fruit. Flowers c. 15 mm across, handsome, white, lilac or violet. Sepals 6-8 mm long. Petals 15-20 mm long, c. 2.5 (-3) mm broad, sparsely and inconspicuously glandular. Stamens c. 6: 8 mm long; anthers c. 2.5 mm long. Siliquae (3-) 5-9 cm long, c. 3 mm broad, glabrous, sparsely or inconspicuously glandular, subtorulose; valves rigid with a distinct mid-vein and a few other parallel veins; seeds c. 3 mm long.