Kesar, also known as Saffron, and is derived from a plant called Crocus sativus. Due to its mélange of benefits and its numerous uses, Kesar is one of the most expensive spices in the world. Kesar (Saffron) promotes learning and memory retention. It is useful in treating old age-related mental impairment. Its herbal properties are used to treat problems like asthma and improve eyesight.