What is "indigofera tinctoria"

Indigo \In"di*go\, a. Having the color of, pertaining to, or derived from, indigo. Indigo berry (Bot.), the fruit of the West Indian shrub Randia aculeata, used as a blue dye. Indigo bird (Zo["o]l.), a small North American finch ( Cyanospiza cyanea). The male is indigo blue in color. Called also indigo bunting. Indigo blue.

1. The essential coloring material of commercial indigo, from which it is obtained as a dark blue earthy powder, with a reddish luster, C16H10N2O2, which may be crystallized by sublimation. Indigo blue is also made from artificial amido cinnamic acid, and from artificial isatine; and these methods are of great commercial importance. Called also indigotin.

2. A dark, dull blue color like the indigo of commerce.

   Indigo brown (Chem.), a brown resinous substance found in crude indigo.

   Indigo copper (Min.), covellite.

   Indigo green, a green obtained from indigo.

   Indigo plant (Bot.), a leguminous plant of several species (genus Indigofera), from which indigo is prepared. The different varieties are natives of Asia, Africa, and America. Several species are cultivated, of which the most important are the Indigofera tinctoria, or common indigo plant, the Indigofera Anil, a larger species, and the Indigofera disperma.

   Indigo purple, a purple obtained from indigo.

   Indigo red, a dyestuff, isomeric with indigo blue, obtained from crude indigo as a dark brown amorphous powder.

   Indigo snake (Zo["o]l.), the gopher snake.

   Indigo white, a white crystalline powder obtained by reduction from indigo blue, and by oxidation easily changed back to it; -- called also indigogen.

   Indigo yellow, a substance obtained from indigo.

Indigo \In"di*go\, n.; pl. Indigoes. [F. indigo, Sp. indigo, indico, L. indicum indigo, fr. Indicus Indian. See Indian.]

1. A kind of deep blue, one of the seven prismatic colors.

2. (Chem.) A blue dyestuff obtained from several plants belonging to very different genera and orders, such as, the woad, Isatis tinctoria (family Cruciferae), Indigofera suffroticosa, Indigofera tinctoria (family Leguminosae), Indigofera Anil, Nereum tinctorium, Polygonum tinctorium Ait. (family Polygonaceae), etc.; called also natural indigo. It is a dark blue earthy substance, tasteless and odorless, with a copper-violet luster when rubbed. Indigo does not exist in the plants as such, but is obtained by decomposition of the glycoside indican.

   Note: Commercial indigo contains the essential coloring principle indigo blue or indigotine, with several other dyes; as, indigo red, indigo brown, etc., and various impurities. Indigo is insoluble in ordinary reagents, with the exception of strong sulphuric acid.

   Chinese indigo (Bot.), Isatis indigotica, a kind of woad.

   Wild indigo (Bot.), the American herb Baptisia tinctoria which yields a poor quality of indigo, as do several other species of the same genus.

Indigofera \In`di*gof"e*ra\, n. [NL., from E. indigo + L. ferre to bear.] (Bot.) A genus of leguminous plants (family Leguminosae) having many species, mostly in tropical countries, several of them yielding indigo, esp. Indigofera tinctoria, Indigofera suffroticosa, and Indigofera Anil.

Indigofera tinctoria, also called true indigo, is a species of plant from the bean family that was one of the original sources of indigo dye. It has been naturalized to tropical and temperate Asia, as well as parts of Africa, but its native habitat is unknown since it has been in cultivation worldwide for many centuries. Today most dye is synthetic, but natural dye from I. tinctoria is still available, marketed as natural coloring where it is known as tarum in Indonesia and nila in Malaysia. In Iran and areas of former USSR known as basma. The plant is also widely grown as a soil-improving groundcover.

True indigo is a shrub one to two meters high. It may be an annual, biennial, or perennial, depending on the climate in which it is grown. It has light green pinnate leaves and sheafs of pink or violet flowers. The plant is a legume, so it is rotated into fields to improve the soil in the same way that other legume crops such as alfalfa and beans are.

Dye is obtained from the processing of the plant's leaves. They are soaked in water and fermented in order to convert the glycoside indican naturally present in the plant to the blue dye indigotin. The precipitate from the fermented leaf solution is mixed with a strong base such as lye.

The rotenoids deguelin, dehydrodeguelin, rotenol, rotenone, tephrosin and sumatrol can be found in I. tinctoria.

Marco Polo (13th century) was the first to report on the preparation of indigo in India. Indigo was quite often used in European easel painting since the Middle Ages.