The yuzu (Citrus ichangensis × C. reticulata, formerly C. junos Siebold ex. Tanaka; Japanese ユズ, 柚, 柚子 (yuzu); 유자 (yuja) in Korean; from Chinese 柚子, yòuzi) is a citrus fruit and plant originating in East Asia. It is believed to be a hybrid of sour mandarin and Ichang papeda. The fruit looks a bit like a very small grapefruit with an uneven skin, and can be either yellow or green depending on the degree of ripeness. Yuzu fruits, which are very aromatic, typically range between 5.5 and 7.5 cm in diameter, but can be as large as a grapefruit (up to 10 cm or larger).
Yuzu forms an upright shrub or small tree, which commonly contains numerous large thorns. Leaves are notable for a large petiole, resembling those of the related kaffir lime and ichang papeda, and are heavily scented. Yuzu closely resemble sudachi in many regards; they share a similar mandarin-ichang papeda ancestry, though sudachi will eventually ripen to an orange color, and there are subtle differences in the flavor of the fruit.