Butterfly Pea, Clitoria ternatea, is also known as Conch Flower. Striking bright purple flowers used as a food colouring, particularly to colour boiled rice blue. Uses in Ayurvedic medicine. Conch Flower is native to Asia and is suitable to most soils in a protected, sunny position. Drought and frost tender. A perennial plant, growing to 4.5m x 4.0m. Flowers in late summer.