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Rubia is a genus of flowering plants in the Rubiaceae family. It contains around 80 species of perennial scrambling or climbing herbs and subshrubs native to the Old World. The genus and its best-known species are commonly known as madder, e.g. Rubia tinctorum (common madder), Rubia peregrina (wild madder), and Rubia cordifolia (Indian madder).
Rubia was an economically important source of a red pigment in many regions of Asia, Europe and Africa. The genus name Rubia derives from the Latin ruber meaning "red".
The plant's roots contain an anthracene compound called alizarin that gives its red colour to a textile dye known as Rose madder. It was also used as a colourant, especially for paint, that is referred to as Madder lake. The synthesis of alizarin greatly reduced demand for the natural compound.
Several species, such as Rubia tinctorum in Europe, Rubia cordifolia in India, and Rubia argyi in east Asia, were extensively cultivated from antiquity until the mid nineteenth century for red dye, commonly called madder. Cloth dyed with it has been found on Egyptian mummies. It was the ereuthedanon (ἐρευθέδανον) used for dyeing the cloaks of the Libyan women in the days of Herodotus. It is the erythrodanon (ἐρυθρόδανον) of Pedanius Dioscorides, who wrote of its cultivation in Caria, and of Hippocrates, and the Rubia of Pliny. R. tinctorum was extensively cultivated in south Europe, France, where it is called garance, and the Netherlands, and to a small extent in the United States. Large quantities were imported into England from Smyrna, Trieste, Livorno, etc. The cultivation, however, decreased after alizarin was made artificially.
Madder was employed medicinally in ancient civilizations and in the middle ages. John Gerard, in 1597, wrote of it as having been cultivated in many gardens in his day, and describes its many supposed virtues, but any pharmacological or therapeutic action which madder may possess is unrecognizable. Its most remarkable physiological effect was found to be that of colouring red the bones of animals fed upon it, as also the claws and beaks of birds. This appears to be due to the chemical affinity of calcium phosphate for the colouring matter. This property was used to enable physiologists to ascertain the manner in which bones develop, and the functions of the various types of cell found in growing bone.
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