Until the invention of
synthetic dyes in the mid-nineteenth century, most dyes came from
plants. Many plants contain substances that can be used to color
fiber, cloth, food, skin, and hair, but very few produce dyes which do not fade rapidly or wash out easily. Producing dyes from plants was complex and time-consuming, and trade secrets were closely guarded.
In Europe's Middle Ages large areas of agricultural land were used to grow dye plants. The most important were Woad (Isatis tinctoria) for blue, Weld (Reseda luteola) for yellow and Madder (Rubia tinctorum) for red. later, as world trade developed, many dyes from tropical plants were used.
Probably the most important and widely used dye, indigo blue, is made from several species of the genus Indigofera. Indigo is the only traditional dye still used commercially (for dying jeans), but mainly in the synthetic version, which is chemically and visually identical to natural indigo.
Saffron, a very expensive dye made from a small part of the Saffron Crocus flower, is mainly used to color and flavor food.
Gorgonzola has told me of murex, from a sea snail that produced a shade of purple so expensive that only kings and emperors wore it.