Saffron (pronounced /ˈsæfrən/ or /ˈsæfrɒn/) is a spice derived from the flower of Crocus sativus, commonly known as the "saffron crocus". The vivid crimson stigma and styles, called threads, are collected and dried for use mainly as a seasoning and colouring agent in food. Saffron has long been the world's most costly spice by weight.