: a plant that yields indigo; especially: any of a genus (Indigofera) of leguminous herbs
Any shrub or herb in the genus Indigofera of the pea family (seelegume). Most occur in warm climates and are silky or hairy. The leaves are usually divided into smaller leaflets. Small rose, purple, or white flowers are borne in spikes or clusters. The fruit is a pod. Some species, particularly I. sumatrana and I. arrecta, were once an important source of indigo dye, a deep navy blue.