The lemon, Citrus limon
(L.) Osbeck, is a species of small evergreen
tree in the flowering plant family Rutaceae,
native to South Asia, primarily North eastern India.
The tree's ellipsoidal
yellow fruit is used for culinary and
non-culinary purposes throughout the world, primarily for its juice,
which has both culinary and cleaning uses.
The pulp and rind (zest) are also used in
cooking and baking. The juice of the lemon is about 5% to 6% citric acid, with a pH
of around 2.2, giving it a sour taste. The distinctive sour taste of
lemon juice makes it a key ingredient in drinks
and foods such as lemonade and lemon meringue pie.