Kaffir Lime leaves are a member of the citrus family responsible for the distinctive lime-lemon aroma and flavour that are an indispensable part of Thai and, to a lesser extent, Indonesian cooking. The leaves of the kaffir lime tree are a dark green color with a glossy sheen. They come in two parts: the top leaflet is lightly pointed at its tip and is attached to another leaflet beneath that is broader on its upper edge. The size of the leaves can vary quite a bit, from less than an inch to several inches long.
The fruit is dark green and round, with a distinct nipple on the stem end. It has a thick rind, knobby and wrinkled, and one of its common names is ‘porcupine orange’. As the fruit becomes older, the color fades to a lighter, yellowish green. Though the juice is infrequently use in cooking, the zest of the rind is often used for making curry pastes.