[custom_adv] Saffron is a spice derived from the flower of Crocus sativus, commonly known as the "saffron crocus". The vivid crimson stigmas and styles, called threads, are collected and dried to be used mainly as a seasoning and colouring agent in food. [custom_adv] Saffron, long among the world's most costly spices by weight, was probably first cultivated in or near Greece. C. sativus is probably a form of C. cartwrightianus, that emerged by human cultivators selectively breeding plants for unusually long stigmas in late Bronze Age Crete. [custom_adv] It slowly propagated throughout much of Eurasia and was later brought to parts of North Africa, North America, and Oceania. [custom_adv] Saffron's taste and iodoform- or hay-like fragrance result from the chemicals picrocrocin and safranal. It also contains a carotenoid pigment, crocin, which imparts a rich golden-yellow hue to dishes and textiles. [custom_adv] Its recorded history is attested in a 7th-century BC Assyrian botanical treatise compiled under Ashurbanipal,[9] and it has been traded and used for over four millennia. Iran now accounts for approximately 90% of the world production of saffron. [custom_adv] The domesticated saffron crocus, Crocus sativus, is an autumn-flowering perennial plant unknown in the wild. It probably descends from the eastern Mediterranean autumn-flowering Crocus cartwrightianus,which is also known as "wild saffron" and originated in Crete or mainland Greece. [custom_adv] An origin in Southwest Asia, although often suspected, has been disapproved by botanical research.The saffron crocus probably resulted when C. cartwrightianus was subjected to extensive artificial selection by growers seeking longer stigmas. C. thomasii and C. pallasii are other possible sources. As a genetically monomorphic clone, it slowly propagated throughout much of Eurasia. [custom_adv] It is a sterile triploid form, which means that three homologous sets of chromosomes compose each specimen's genetic complement; C. sativus bears eight chromosomal bodies per set, making for 24 in total. Being sterile, the purple flowers of C. [custom_adv] sativus fail to produce viable seeds; reproduction hinges on human assistance: clusters of corms, underground, bulb-like, starch-storing organs, must be dug up, divided, and replanted. A corm survives for one season, producing via this vegetative division up to ten "cormlets" that can grow into new plants in the next season.