There are several different types of limes, including the Mexican lime, kaffir lime, Italian lime and the Mandarin lime. These limes are native to different areas of the world, but all lime trees come from warm, tropical regions. Lime trees can be identified by examining the tree, its leaves and its fruit.
Look for spines. Mexican lime trees have very sharp, needle-shaped spines that are 3/8-inch long and which can cause injury. Italian lime trees have very few spines, while the spines of the kaffir and Mandarin lime trees are shorter.
Determine the size of the tree. Mexican lime trees can range in height from 6 to 13 feet. Italian lime trees can grow to be 20 feet, as can Mandarin lime trees. The kaffir lime tree is shorter, only growing to about 16 feet.
Examine the leaves of the tree. A Mexican lime tree will usually have oval-shaped lime-green colored leaves that are 2 inches long and 1 to 2 inches wide. The leaves of an Italian lime tree will be purple when young, turning green upon maturity. The Mandarin lime tree has smaller, oval-shaped green leaves. The kaffir lime tree has leaves that grow up to 2 inches in length and are broad in shape.
Examine the flowers, if any are present. Common lime blossoms are small, star-shaped white flowers with five petals and a yellow center. Italian lime blossoms grow in clusters of up to 10, while kaffir lime trees and Mandarin lime trees have flowers similar to the common lime.
Examine the fruit of the tree. Not all limes are small, oval-shaped green fruit. If the lime resembles an average, dark greenish yellow lime that would be found in a grocery store, it is a Mexican lime. These limes are also called Key limes or common limes. If the skin of the fruit is bumpy or lumpy-looking, the lime is a kaffir lime. If the fruit is yellow and very round, it could be an Italian lime or limetta, which is a lime-lemon hybrid. If the fruit is round, orange and lumpy, it is a Mandarin lime, which resembles an orange but tastes like a lime. The fruit of most lime trees grows in clusters of two to three fruits.