Dense, suckering shrub, pea-like flowers which bloom heavily in June and July and sometimes continue intermittently to September. Needs long growing season. Blooms on new growth. Used for many years to produce indigo dyes. Ancient dyeplant known for the clarity and fastness of the blue produced. Leaves contain indican which must be oxidized by fermentation to produce the dye. Fresh herbage (strongest when in flower) is steeped in water for 12-48 hours with frequent stirring. A blue sediment will form which is the dye.