The Kaffir Lime is a type of citrus tree that produces exceptionally fragrant fruits and leaves that impart unique flavors that have become identified with Thai cuisine. The luscious perfume and striking flavor of the leaves cannot be easily substituted with other kinds of citrus leaves. They are worth seeking, as their special attributes are irreplaceable. The average tree grows from 8-15 ft. high and equally wide. The dark green fruit is roughly the same size of a Western lime and has a bumpy surface. The juice is seldom used in cooking but the peel of the fruit, with its high concentration of aromatic oils, is indispensable in many curry pastes and is one reason why Thai curries taste refreshingly unique. The zest also imparts a wonderful piquant.