Koji orange

Koji orange, also known as the smooth-fruited orange, is a Citrus species native to Japan. The specific epithet comes from the Greek , and . It is a taxonomical synonym of Citrus aurantium.

Distribution

Besides Japan, it is grown in the United States, and other parts of East Asia including South Korea and China.

Description

The fruit is oblate in shape, slightly ribbed, bright orange in color, very small, and very seedy, and for the latter two reasons it is not grown for commercial use. It ripens from October through November and has been cultivated since at least 1900. It may be monoembryonic. The tree is densely branched and has a broad crown and a short, straight trunk. The leaves are dark green and elliptical in shape.

Genetics

Citrus leiocarpa is inferred to be a hybrid between a koji-type species and the tachibana orange. Its genotype matches with that of the komikan and toukan varieties.

Varieties

Citrus leiocarpa f. monoembryota, a form of Citrus leiocarpa, was described by Chozaburo Tanaka. Once believed to be a mutation of the koji orange, it has been revealed that it is a hybrid between koji and kishu. In Chinese, it is called 駿河柑子 and is called スルガユコウ and 駿河柚柑 in Japanese.