indigofera

Indigofera is a genus of flowering plants in the legume family, Fabaceae. It comprises several hundred species of shrubs, trees, and herbaceous plants native to tropical and subtropical regions of Africa, Asia, and the Americas. The name is linked to the historical use of some species as a source of indigo dye.

Most Indigofera species have pinnate leaves with multiple leaflets. They produce small pea-like flowers arranged in racemes or spikes, typically in shades of pink to purple. The fruit is a legume pod containing seeds. The plants vary in size from delicate groundcovers to short woody shrubs, with a generally bushy or upright habit.

The best-known species for natural indigo dye are Indigofera tinctoria and Indigofera suffruticosa. Leaves contain indican, which can be hydrolyzed and oxidized to yield indigo pigment. Historically, fermentation and oxidation of leaf extracts produced blue textiles, and indigo dye played a major role in textile industries worldwide. Today, most indigo dye is synthetic, but natural indigo from Indigofera is still produced on a smaller scale in some regions.

Beyond dye production, Indigofera species are valued in horticulture for their ornamental flowers and drought tolerance. Many members fix nitrogen through symbiotic bacteria in root nodules, making them useful as cover crops or green manures in some cropping systems. They are also used in traditional medicines and as fodder in various cultures, depending on the species.