Curacao is a liqueur flavored with the dried peel of the laraha citrus fruit, grown on the island of Curaao. A non-native plant similar to an orange, the laraha developed from the sweet Valencia orange transplanted by Spanish explorers. The nutrient-poor soil and arid climate of Curaao proved unsuitable to Valencia cultivation, resulting in small bitter fruit on the trees. But the aromatic peel maintained much of the essence of the Valencia varietal, and the trees were eventually bred into the current laraha cultivar, whose fruits remain inedibly bitter.
Contributions by SmackBot, Rees11, and Epastore.