Saffron is one of the world's most expensive spices by weight due to its difficulty to harvest. Saffron consists of stigmas plucked from the vegetatively propagated and sterile Crocus sativus, known popularly as the saffron crocus. The resulting dried "threads" are distinguished by their bitter taste, hay-like fragrance, and slight metallic notes. The saffron crocus is unknown in the wild; its most likely precursor, Crocus cartwrightianus, originated in Crete or Central Asia; The saffron crocus is native to Southwest Asia, and is believed to have been first cultivated in Iran. Greece, Turkey, and Kashmir (India) have also been suggested as possible sites of origin."Saffron, for example, was once less regarded than it is today because the crocus from which it is extracted was not particularly mysterious. It flourished in European locations extending from Asia Minor, where it originated, to Saffron Walden in England, where it was naturalised. Only subsequently, when its labour-intensive cultivation became largely centred in Kashmir (India), did it seem sufficiently exotic to qualify as one of the most precious of spices."