''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 Indigo dye is an organic compound with a distinctive blue color. Historically, indigo was a natural dye extracted from the leaves of some plants of the ''Indigofera'' genus, in particular '' Indigofera tinctoria''; dye-bearing ''Indigofera'' pl ...

Description

True indigo is a shrub one to two meters high. It may be an

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

biennial Biennial means (an event) lasting for two years or occurring every two years. The related term biennium is used in reference to a period of two years. In particular, it can refer to: * Biennial plant, a plant which blooms in its second year and th ...

, or

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...

, depending on the climate in which it is grown. It has light green

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...

leaves and sheafs of pink or violet flowers. The

rotenoid Rotenoids are naturally occurring substances containing a cis-fused tetrahydrochromeno ,4-bhromene nucleus. Many have insecticidal activity, such as the prototypical member of the family, rotenone. Rotenoids are related to the isoflavones. Natu ...

s deguelin, dehydrodeguelin, rotenol,

rotenone Rotenone is an odorless, colorless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant, and the roots of several mem ...

tephrosin Tephrosin is rotenoid. It is a natural fish poison found in the leaves and seeds of ''Tephrosia purpurea'' and '' T. vogelii''.Production of rotenoids by heterotrophic and photomixotrophic cell cultures of tephrosia vogelii. Nadine Lambert, Marie- ...

and sumatrol can be found in ''I. tinctoria''.

Distribution and habitat

It has been naturalized to tropical and temperate

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

, as well as parts of

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, but its native habitat is unknown since it has been in cultivation worldwide for many centuries.

Agricultural use

The plant is a

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock for ...

, so it is rotated into fields to improve the soil in the same way that other legume crops such as

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...

and

bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...

s are. The plant is also widely grown as a soil-improving

groundcover Groundcover or ground cover is any plant that grows over an area of ground. Groundcover provides protection of the topsoil from erosion and drought. In an ecosystem, the ground cover forms the layer of vegetation below the shrub layer known as ...

Dye

Dye is obtained from the processing of the plant's leaves. They are soaked in water and

fermented Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...

in order to convert the

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

indican naturally present in the plant to the blue dye

indigotin Indigo dye is an organic compound with a distinctive blue color. Historically, indigo was a natural dye extracted from the leaves of some plants of the ''Indigofera'' genus, in particular '' Indigofera tinctoria''; dye-bearing ''Indigofera'' p ...

. The precipitate from the fermented leaf solution is mixed with a strong base such as lye. Today most dye is synthetic, but

natural dye Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources— roots, berries, bark, leaves, and wood—and other biological sources such as fungi. Ar ...

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 the former

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...

it is known as ''basma''.

History

Marco Polo Marco Polo (, , ; 8 January 1324) was a Venetian merchant, explorer and writer who travelled through Asia along the Silk Road between 1271 and 1295. His travels are recorded in '' The Travels of Marco Polo'' (also known as ''Book of the Marv ...

(13th century) was the first European to report on the preparation of indigo in India. Indigo was quite often used in European easel painting, beginning in the Middle Ages.Pigments through the ages
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References

External links

* tinctoria Plant dyes Flora of temperate Asia Plants described in 1753 Taxa named by Carl Linnaeus Groundcovers {{faboideae-stub