Isatis Tinctoria

Isatis tinctoria, with Woad ( /ˈwoʊd/; or glastum) as the common name, is a flowering plant in the family Brassicaceae. It is commonly called dyer's woad, and sometimes incorrectly listed as Isatis indigotica (a newer and invalid name for the same plant). It is occasionally known as Asp of Jerusalem. Woad is also the name of a blue dye produced from the leaves of the plant.

Woad is native to the steppe and desert zones of the Caucasus, Central Asia to eastern Siberia and Western Asia (Hegi), but is now found in southeastern and some parts of Central Europe as well. Long important as a source of blue dye, it has been cultivated throughout Europe, especially in Western and southern Europe, since ancient times. In medieval times there were important woad growing regions in England, Germany and France, and towns such as Toulouse became prosperous on the woad trade. Woad was eventually replaced by the stronger indigo and then by synthetic indigoes.