Shimen, Hunan, has a long history of planting citrus. As early as more than 2,000 years ago, the great patriotic poet Qu Yuan wrote the famous poem "Ode to Oranges" in his hometown. According to research, citrus originated from the Yunnan-Guizhou Plateau in my country, passed down the Yangtze River, and spread to the south of the Huaihe River. The lower reaches of the Yangtze River to the Lingnan region. After long-term cultivation by our people. Choice, citrus has become a precious fruit for mankind.
Citrus classification is an important knowledge and technology in the cultivation and utilization of citrus trees. During the Warring States Period (the third century BC), it was known that tangerines, oranges, and tangerines belong to the same category of fruit trees. The ancient book "Yiyuan" from the Northern and Southern Dynasties classified "tangerines, tangerines, oranges, and pomeloes" into categories. The book "Compendium on Materia Medica" of the Tang Dynasty records five types of citrus including "zhu tangerine, milk tangerine, yellow tangerine, stone tangerine, and sand tangerine" and five types of tangerines: "zhu tangerine, rut orange, tan tangerine, mountain tangerine, and yellow tangerine." ", and described that "there are pomeloes in Lingnan as big as winter melons." The world's first citrus monograph - "Ju Lu" uses almost three-fifths of its space to record the real tangerines, raw tangerines, sea red tangerines, Dongting tangerines, red tangerines, kumquats, wood tangerines, sweet tangerines, oranges, Yellow orange, flat orange, bag orange, cotton orange, sand orange, lychee orange, soft strip orange, oil orange, green orange, milk orange, kumquat, natural orange, early yellow orange, frozen orange, Zhu Luan, Xiang Luan 27 kinds of citrus including citrus, xiangyuan, tangerine and so on. He described the characteristics of the variety from the size and shape of the fruit, the color of the peel, the ease of peeling, the number of pods, flavor, number of seeds, maturity time, and crown shape, and pointed out the basis for naming, which is the modern definition of citrus varieties. The description is nothing more than these contents.