Woad
A European plant whose leaves give a blue dye, the same colouring matter as indigo.
Also: pastel (dye), dyer's woad
Woad is a yellow-flowered plant of the cabbage family. Its leaves contain the same blue dye as tropical indigo, though much less of it. Until the 17th century it was the main source of blue for European cloth. The leaves were crushed, rolled into balls, dried and fermented, a smelly business. Towns such as Toulouse in France and Erfurt in Germany grew rich on the trade. Imported indigo, stronger and cheaper, gradually pushed woad out despite laws passed to protect the growers.