Navel orange [qí chéng], original name: sweet orange. Alias: Huangguoshu, orange, navel orange, fragrant orange, orange. Latin name: Citrus sinensis (L.) Osbeck. Rutaceae, small evergreen tree of the family Rutaceae, with hairless branchlets and short or no thorns. The leaves are elliptical or ovate, with entire margin or blunt teeth; the petiole has narrow wings and a joint at the top. Navel orange is an improved citrus variety cultivated in various countries around the world. At present, many high-quality navel oranges are also cultivated in various parts of our country. Navel oranges are rich in nutrients and contain various nutrients necessary for the human body. Navel oranges contain a large amount of vitamin C and carotene, which help inhibit the formation of carcinogens, soften and protect blood vessels, promote blood circulation, help lower cholesterol and blood lipids, reduce the possibility of heart disease, and prevent gallbladder disease. Navel oranges are rich in vitamins and can prevent the occurrence of scurvy. The fruit is orange-yellow with green markings. Suitable for potted plants, it is a good product for viewing leaves and fruits. In 1820, an orange tree mutated in a monastery in Brazil. Each orange had a small orange at the end. At the same time, all the oranges in the tree were seedless, so they could not be grown from seeds and could only be grafted. In 1870, two navel orange trees were successfully grafted in California, USA, and the worldwide popularity of navel oranges began. Even today, the only way to grow navel oranges is by grafting, so today’s navel oranges are genetically identical to the original ancestral tree in Brazil. Navel oranges were first successfully experimented by a Zhejiang native in the United States. Chinese navel oranges were introduced from the United States only a few decades ago.