true indigo

True indigo, scientifically known as Indigofera tinctoria, is a plant species belonging to the pea family (Fabaceae). This genus, Indigofera, comprises over 750 species of shrubs, trees, and herbs native to tropical and subtropical regions worldwide.1

Historically, true indigo and Natal indigo (I. arrecta) were significant sources of indigo dye. The cultivation and extraction of this dye were once a major industry, particularly in India. However, the development of synthetic indigo in the early 20th century gradually led to the decline of natural indigo production.1

Indigo plants are characterized by their compound leaves, and their flowers are typically rose, purple, or white, borne in spikes or clusters. The fruit is a pod. The natural precursor to indigo dye is indican, which can be converted to indigo through mild oxidation.12