Alizarin, which consists of 1,2 dihydroxyanthraquinone, is the common madder of anthraquinoid pigment group. It has been used for textiles, food and medicine. The colour of alizarin is light brown and dissociates low in water. It is in the root of Rubia tinctorum plant. The plant is 50-80 cm high and its trunk is cornered, hard and thorny.