More info on Umeshu and Ume (Plum) in Wikipedia :
Ume is the Japanese name for a species of Asian plum (Prunus mume, Rosaceae). The tree originates from China (where it is called méi), but has also grown in Japan and Korea (where it is called maesil) since ancient times. The tree is cultivated for its fruits and flowers. Although normally called a plum, it is actually more closely related to the apricot. Another species commonly referred to as the "Japanese plum" is the sumomo.
Culinary use
Ume juice is extracted by preserving the fruits in sugar. It tastes sweet and acidic, and is a refreshing drink, often enjoyed in the summer. In Korea, maesil juice, which is marketed as a healthful tonic, is enjoying increasing popularity. Umeshu (also called plum wine) is a Japanese alcoholic drink made by steeping green ume in shochu (clear liquor). It is sweet and smooth. The taste and aroma of ume-shu can appeal to even those people who normally dislike alcohol. A similar product, called maesilju, mae hwa su, or mae chui soon, is produced in Korea.
Medicinal use
The fruit, as used in traditional Chinese medicine, is called wu mei. It is believed to be effective against parasites, as well as in stopping ulcers and promoting a strong digestive system and heart.
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http://en.wikipedia.org/wiki/Ume