Grown in Southeast Asia and Hawaii, the kaffir lime tree produces small, pear-shaped citrus fruit with a skin that's bright yellow-green, bumpy and wrinkled. The glossy, dark green kaffir lime leaves, which are used in cooking (particularly in Thai cuisine), have a unique double shape and look like two leaves that are joined end to end. Dried kaffir lime rind and leaves, which have a mysterious flora-citrus aroma, can be found in Asian markets. Fresh leaves, which have a more intense, fragrant aroma, are sometimes also available.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.