Madder is an evergreen plant native to the Old World. This plant has historically been used as a source of animal fodder, but it was commercially important for its red root, which was used to manufacture a dye known as madder or rose madder. Madder roots produce a variety of reds including orange reds, brick red, blood red and fiery reds. The colour depends on the soil the roots where grown, their age, the mineral content of the water used for dyeing, the temperature of the dye pot, and how much madder you use in relation to the fibre. You can dye with madder either cold or with heat. Add chalk and avoid high temperature to get better reds. Several dyers recommend mordanting the wool just with alum, not using cream of tartar as well. Madder can be used on cotton, leather, wool and silk.