page_title: Isatis tinctoria
section_title: Woad and indigo
hierarchical_section_title: Isatis tinctoria / Woad and indigo
caption_attribution_description: English: Isatis tinctoria, Brassicaceae, Woad, Indigo from Isatis tinctoria; Staatliches Museum für Naturkunde Karlsruhe, Germany. Deutsch: Isatis tinctoria, Brassicaceae, Färberwaid, Deutscher Indigo, Indigo aus Isatis tinctoria; Staatliches Museum für Naturkunde Karlsruhe, Deutschland.
context_page_description: Isatis tinctoria, also called woad, dyer's woad, or glastum, is a flowering plant in the family Brassicaceae. 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 but is now also found in South-Eastern and Central Europe and western North America.
  Since ancient times, woad was an important source of blue dye and was cultivated throughout Europe, especially in Western and Southern Europe. In medieval times there were important woad-growing regions in England, Germany and France. Towns such as Toulouse became prosperous from the woad trade. Woad was eventually replaced by the more colourfast Indigofera tinctoria and, in the early 20th century, both woad and Indigofera tinctoria were replaced by synthetic blue dyes. Woad has been used in traditional Chinese medicine for centuries. There has also been some revival of the use of woad for craft purposes.
context_section_description: The dye chemical extracted from woad is indigo, the same dye extracted from "true indigo", Indigofera tinctoria, but in a lower concentration.  Following the Portuguese discovery of the sea route to India by the navigator Vasco da Gama in 1498, great amounts of indigo were imported from Asia. Laws were passed in some parts of Europe to protect the woad industry from the competition of the indigo trade. It was proclaimed that indigo caused yarns to rot: "In 1577 the German government officially prohibited the use of indigo, denouncing it as that pernicious, deceitful and corrosive substance, the Devil's dye." This prohibition was repeated in 1594 and again in 1603. In France, Henry IV, in an edict of 1609, forbade under pain of death the use of "the false and pernicious Indian drug".
  With the development of a chemical process to synthesize the pigment, both the woad and natural indigo industries collapsed in the first years of the 20th century. The last commercial harvest of woad until recent times occurred in 1932, in Lincolnshire, Britain. Small amounts of woad are now grown in the UK and France to supply craft dyers. The classic book about woad is The Woad Plant and its Dye by J. B. Hurry, Oxford University Press of 1930, which contains an extensive bibliography.
  A method for producing blue dye from woad is described in The History of Woad and the Medieval Woad Vat (1998) ISBN 0-9534133-0-6.
  Woad is biodegradable and safe in the environment. In Germany, there have been attempts to use it to protect wood against decay without applying dangerous chemicals. Production of woad is increasing in the UK for use in inks, particularly for inkjet printers, and dyes. The plant can cause problems, however: Isatis tinctoria is classified as an invasive species in parts of the United States.
caption: Indigo extracted from woad
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