Lemon (Citrus × limon) is a small evergreen tree native to Asia. The tree's ellipsoidal yellow fruit is used for culinary and non-culinary purposes throughout the world, primarily for its juice, though the pulp and rind (zest) are also used in cooking and baking. The juice of the lemon is about 5% to 6% citric acid,which gives lemons a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in drinks and foods such as lemonade.The origin of the lemon is a mystery,though it is thought that lemons first grew in Assam (a region in Northeast India), northern Burma, and China. A study of the genetic origin of the lemon reported that it is a hybrid between sour orange and citron. Lemons were known to the Jews of Jerusalem,according to Josephus, pelted an errant high priest with them during a festival in the 90s BC, although Jewish tradition maintains that this was done with citrons, not lemons. They entered Europe near southern Italy no later than the 1st century AD, during the time of Ancient Rome. However, they were not widely cultivated. They were later introduced to Persia and then to Iraq and Egypt around 700 AD. The lemon was first recorded in literature in a 10th-century Arabic treatise on farming, and was also used as an ornamental plant in early Islamic gardens.