Family Rubiaceae, composed of about 6,500 species of herbs, shrubs, and trees in 500 genera. The leaves usually are large and evergreen in tropical species, deciduous in temperate species, and needlelike or scalelike in desert species. The plants may bear a single flower or many small flowers clustered together. Economically important products of the family include coffee, quinine, ipecac, the red dye alizarin (from the roots of common madder, Rubia tinctorum, and of R. cordifolia), and ornamentals including gardenias.
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The Common Madder can grow to 1.5 m in height. The evergreen leaves are 5-10 cm long and 2-3 cm broad, produced in whorls of 4-7 starlike around the central stem. It climbs with tiny hooks at the leaves and stems. The flowers are small (3-5 mm across), with five pale yellow petals, in dense racemes, and appear from June to August, followed by small (4-6 mm diameter) red to black berries. The roots can be over a metre long, up to 12 mm thick and the source of a red dye known as rose madder. It prefers loamy soils with a constant level of moisture. Madders are used as food plants for the larvae of some Lepidoptera species including Hummingbird hawk moth.
The roots contain the acid ruberthyrin. By drying, fermenting or a treatment with acids, this is changed to sugar, alizarin and purpurin. Purpurin is normally not coloured, but is red when dissolved in alcalic solutions. Mixed with clay and treated with alum and ammonia, it gives a brilliant red colourant (madder lake).
The pulverised roots can be dissolved in sulfuric acid, which leaves a dye called garance (the French name for madder) after drying. Another method of increasing the yield consisted of dissolving the roots in sulfuric acid after they had been used for dyeing. This produces a dye called garanceux. By treating the pulverized roots with alcohol, colorin was produced. It contained 40-50 times the amount of alizarin of the roots.
The chemical name for the pigment is alizarin, of the anthraquinone-group. In 1869, the German chemists Graebe and Liebermann synthesised artificial alizarin, which was produced industrially from 1871 onwards, which effectively put an end to the cultivation of madder. In the 20th century, madder was only grown in some areas of France.
According to Culpeper's herbal, the plant is ruled by Mars and has an opening quality, and will bind and strengthen afterwards. It was used in the treatment of jaundice, obstruction of the spleen, melancholy, palsy, haemorrhoids, sciatica, and of bruises. The root should be boiled in wine, and sugar or honey added. The seed of madder, drunk with vinegar and honey is used for the swelling of the spleen. Leaves and stems are used when the monthly female menstrual bleeding is late. Leaves and roots are squashed and put on freckles and other discolorations of the skin.