Saffron is a spice derived from the flower of the saffron crocus (Crocus sativus), a species of crocus in the Iridaceae. A C. sativus flower bears three stigmas, each the distal end of a carpel. Together with their styles—stalks connecting stigmas to their host plant—stigmas are dried and used in cooking as a seasoning and colouring agent. Saffron, long the world's most expensive spice by weight, is native to Southwest Asia.