Galega colutea Burm.f.
Indigofera consanguinea Klotzsch
Indigofera junodii N.E.Br.
Indigofera propinqua Hochst.
Indigofera seticulosa Harv.
Indigofera viscosa Lam.
Indigofera colutea is a procumbent to prostrate, annual to short-lived perennial plant with branching stems; it can grow 10 - 90cm tall[
The plant is harvested from the wild for local use as a medicine. It is a local source of the widely used dyestuff 'indigo'.
Widespread through tropical and subtropical Africa and Asia from Cape Verde to Indonesia, New Guinea, eastern Australia, New Zealand
Grassland; cultivations; open spots in bushland; especially on sandy soil; sandy muddy soil; grassy formation with Schoenefeldia gracilis; rocky places; deciduous woodland or bushland; at elevations up to 1,500 metres[
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Indigoera species generally grow best in a sunny position, preferring a well-drained but moist soil[
]. Many of the species will also succeed in drier conditions and in poor soils.
There are viscid glands on the stems, making the plant strongly aromatic and sticky[
This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.
The roots are used as a healing medicine[
The whole plant is used in the treatment of stomach aches[
The plant (?stem hairs, ?leaves) is used to treat cutaneous and subcutaneous parasitic infections[
An aqueous acetone extract of the leaves and stems is rich in polyphenols and flavonoids and has been shown to be an effective antioxidant[
The leaves are a source of the dyestuff 'indigo'[
The leaves and twigs do not actually contain indigo but colourless precursors that must be extracted and then processed in order to produce the indigo dye[
The harvested leafy branches are placed in a tank containing water to which some lime has been added, and are weighted down with planks[
]. After some hours of fermentation, during which enzymic hydrolysis leads to the formation of indoxyl, the liquid is drained off and then stirred continuously for several hours to stimulate oxidation of the indoxyl[
]. Afterwards the solution is left to rest and the insoluble indigo settles to the bottom as a bluish sludge[
]. The water is drained and after the indigo has dried, it is cut into cubes or made into balls[
To dye textiles, indigo is reduced to a soluble form by a fermentation process under alkaline conditions. In traditional preparations of the dye, various reducing agents such as molasses are used, together with coconut-milk, bananas and the leaves of Psidium guajava[
]. The alkalinity is maintained by adding lime. After the textile has been dipped into solution it turns blue when exposed to the air[
Seed - it has a hard seedcoat and may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing.
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