The most economically important genus in the family is Citrus, which includes the orange (C. sinensis), lemon (C. × limon), grapefruit (C. paradisi), and lime (various, mostly C. aurantifolia, the key lime). Boronia is a large Australian genus, some members of which are plants with highly fragrant flowers and are used in commercial oil production. Other large genera include Zanthoxylum, Melicope and Agathosma. There are approximatively 160 genera in the family Rutaceae:List of Rutaceae genera
The lemon (Citrus × limon) is a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The 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.