Isatis tinctoria

Isatis tinctoria, also called woad (/ˈwoʊd/), 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 (per Hegi) 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. The first archaeological finds of woad seeds date to the Neolithic. The seeds have been found in the French cave of l'Audoste, Bouches-du-Rhône, France. Impressions of seeds of Färberwaid (Isatis tinctoria L.) or German indigo, of the plant family Brassicaceae, have been found on pottery in the Iron Age settlement of Heuneburg, Germany. Seed and pod fragments have also been found in Iron Age pit at Dragonby, North Lincolnshire, United Kingdom. The Hallstatt burials of the Hochdorf Chieftain's Grave and Hohmichele contained textiles dyed with woad dye. Melo and Rondão write that woad was known 'as far back as the time of the ancient Egyptians, who used it to dye the cloth wrappings applied for the mummies.' Skelton informs us that one of the early dyes discovered by the ancient Egyptians was 'blue woad (Isatis tinctoria).' Lucas writes, 'What has been assumed to have been Indian Indigo on ancient Egyptian fabrics may have been woad.' Hall states that the ancient Egyptians created their blue dye 'by using indigotin, otherwise known as woad.' Celtic blue is a shade of blue, also known as glas celtig in Welsh, or gorm ceilteach in both the Irish language and in Scottish Gaelic. Julius Caesar reported (in Commentarii de Bello Gallico) that the Britanni used to colour their bodies blue with vitrum, a word that means primarily 'glass', but also the domestic name for the 'woad' (Isatis tinctoria), besides the Gaulish loanword glastum (from Proto-Celtic *glastos 'green'). The connection seems to be that both glass and the woad are 'water-like' (lat. vitrum is from Proto-Indo-European *wed-ro- 'water-like'). In terms of usage, Latin vitrum is more often used to refer to glass rather than woad. The use of the word for the woad might also be understood as 'coloured like glass', applied to the plant and the dye made from it. Due to this and other Roman accounts of them painting (or possibly tattooing) their bodies, northern inhabitants of Britain came to be known as Picts (Picti), meaning 'painted ones' in Latin. Gillian Carr conducted experiments using indigo pigment derived from woad mixed with different binders to make body paint. The resulting paints yielded colours from 'grey-blue, through intense midnight blue, to black'. People with modern experiences with woad as a tattoo pigment have claimed that it does not work well, and is actually caustic and causes scarring when put into the skin. It has also been claimed that Caesar was referring to some form of copper- or iron-based pigment. Analysis done on the Lindow Man did return evidence of copper. The same study also noted that the earliest definite reference to the woad plant in the British Isles dates to a seed impression on an Anglo-Saxon pot. The authors theorize that vitrum could have actually referred to copper(II) sulfate's naturally occurring variant chalcanthite or to the mineral azurite. A later study concluded the amount was 'not of sufficient magnitude to provide convincing evidence that the copper was deliberately applied as paint'. Woad was an important dyeing agent in much of Europe and parts of England during the medieval period. However, dye traders began to import indigo during the sixteenth and seventeenth centuries, which threatened to replace locally grown woad as the primary blue dye. The translation of vitrum as woad may date to this period.