Isatis tinctoria

Isatis tinctoria, known as woad, dyer's woad, dyer's-weed, or glastum, is a flowering plant from the mustard family. Its history includes use as both a blue dye and a medicinal herb. The name Isatis points to its ancient role in treating wounds, while tinctoria refers to dyeing.

It is sometimes called Asp of Jerusalem. The term "woad" also describes the blue dye made from the plant's leaves. Originally native to steppe and desert areas from the Caucasus and Central Asia through Eastern Siberia and Western Asia, it now also grows in parts of South-Eastern and Central Europe and western North America.

Medieval period onwards

Woad was a major source of blue dye, cultivated across Europe, especially in the west and south. During medieval times, key growing regions included England, Germany, and France. Towns like Toulouse grew wealthy from the woad trade.

Cultivation spread throughout Europe, making woad an important trade item. Starting in the 16th century, indigo (Indigofera tinctoria), from Subsaharan Africa and South and Southeast Asia, began to replace it. By the early 20th century, both woad and indigo had largely been replaced by synthetic blue dyes, though woad has seen some revival for craft use.

Ancient use

The earliest archaeological evidence of woad seeds dates to the Neolithic period, found in a cave in Bouches-du-Rhône, France. Impressions of woad seeds appear on Iron Age pottery from Heuneburg, Germany, and seed and pod fragments were found in an Iron Age pit at Dragonby, North Lincolnshire, UK. Textiles dyed with woad were discovered in the Hallstatt burials of the Hochdorf Chieftain's Grave and Hohmichele. It is very likely woad was used as a dye in ancient Egypt.

A passage from Julius Caesar's Commentaries on the Gallic War describes Britons painting themselves with vitrum, which produces a dark blue color, making them look more frightening in battle. Vitrum is often translated as "woad," but more commonly means "glass." Experimental body paints made from woad with different binders produced colors ranging from grey-blue to intense midnight blue to black. While some have argued woad was used for tattooing, experiments have failed due to its caustic nature. Analysis of the Lindow Man bog body from the late Iron Age or early Roman period suggests Britons may have used a copper- or iron-based pigment for body decoration.