Yuzu

This fruit resembles a yellow clementine with 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 (2+1⁄8 and 3 in) in diameter but can be as large as the more familiar grapefruit (up to 10 cm or 4 in, or larger).Yuzunone, an odor-active volatile identified in yuzu peel oil, has been found to contribute greatly to yuzu's distinctive aroma. Yuzu forms as an upright shrub or small tree, which commonly has many large thorns. Leaves are notable for a large, leaf-like petiole, resembling those of the related makrut lime and ichang papeda, and are heavily scented. Yuzu closely resembles sudachi (Citrus sudachi, a Japanese citrus from Tokushima Prefecture, a yuzu–mandarin orange cross) in many regards, though, unlike the sudachi, yuzu eventually ripen to an orange color and there are subtle differences between the flavors of the fruit.

The yuzu originated and grew wild in Tibet and central China. It was introduced to Japan and Korea during the Tang dynasty and is still cultivated there. It grows slowly, generally requiring ten years to fruit. To shorten the duration to fruiting, it may be grafted onto karatachi (P. trifoliata). It is unusual among citrus plants in being relatively frost-hardy, due to its cold-hardy Ichang papeda ancestry, and can be grown in regions with winters as low as −7 °C (19 °F) where more sensitive citrus would not thrive.