Indigofera suffruticosa aka Anil Indigo

Indigofera suffruticosa also goes by the name anil indigo. It belongs to Fabaceae, the pea family. Its native range spans tropical and subtropical parts of the Americas. It reaches from Argentina and Paraguay north to Florida. It also grows through Central America and the Caribbean. It grows in fields, thickets, waste ground, and on sandbars. Most sites lie on low ground, though some lie higher.

This upright shrub has few branches and keeps its leaves year-round. It is a perennial, so it lives for several years. In gardens, it reaches about 5 feet (1.5 metres) tall and wide. Broader accounts give heights of 1.5–8.2 feet (0.45–2.5 metres). Its woody rootstock bears stems that may become woody too. Some stems stay soft; woody stems last beyond one year. Its leaves are pinnate: leaflets grow along a central stalk. The plant grows fast. One source gives its bloom time as late winter to early spring. Its fruit forms pods that split and release black seeds.

It suits tropical and subtropical gardens but cannot stand frost. PFAF lists it for USDA zones 10–12. It grows in full sun or light shade. It accepts sandy, loamy, and clay soils that drain well. Rich, silty-sandy soil suits it, but it grows in poor soil too. It grows in acid to neutral soil, even very acid ground. The soil may be dry or moist. Once its roots take hold, it can cope with drought. Root bacteria form nodules, or small lumps, that take nitrogen from the air.

Anil indigo has long served as a blue dye crop. Growers in Central America once raised it on a large scale. Man-made dyes later cut demand for the crop. Farmers also grow it as green manure and ground cover. For these uses, they plant it among coffee, rubber, and tea crops. Its roots fix nitrogen and can help make soil more fertile. Other uses include contour hedges, which follow the land's level lines. People also manage it by coppicing, cutting stems back for new growth. It can become a weed on farmed land. The sources differ on its wider weed risk.

The supplied sources list no known edible uses. Water extracts of its fruit have caused liver damage and chromosome changes. Past uses in folk medicine include roots for stomach pain. People have also used leaves for fever and indigo on insect stings. The source doubts whether the sting treatment works. These reports record past uses, not proven benefits or safe treatments.