What plants are used in ink?

Several plants are used to produce natural inks, including indigo from the indigo plant for blue dye, and madder root for red hues. Other sources include logwood, which yields a deep purple, and walnut hulls, known for their rich brown color. Additionally, various berries, such as blackberries and Elderberries, can be used for their pigments. These natural inks have been utilized historically for writing and artistic purposes.