Southern orange and northern orange (pinyin: nán jú běi zhǐ) is an idiom, which comes from Yan Zi Chun Qiu Nei Zapian. Orange in the south and orange in the north mean that oranges in the south will become oranges when transplanted to the north of Huaihe River, which is a different plant from oranges. The ancients mistakenly thought that oranges in the south would become oranges when transplanted to the north of Huaihe River, which means that the same species varies due to different environmental conditions.

Fructus Aurantii: Deciduous shrub, bitter and sour, spherical. Also called orange. Oranges in the south will become bitter oranges when transplanted to the north of Huaihe River. Metaphor means that the same species varies due to different environmental conditions. Later generations used "orange in the south and orange in the north" to describe the influence of environment on people. In modern Chinese, it seems to be used in a slightly derogatory place to describe something "alienated" or "deteriorated" because of the change of environment.

Historical story of southern orange and northern orange;

Yan Zi's Spring and Autumn Annals: "Those who grow in the south of Huaihe River are bitter oranges, while those who grow in the north of Huaihe River turn into bitter oranges, but the leaves are similar and the fruit tastes different. Why is this happening? Because the soil and water are different. " Diplomacy is no small matter, especially involving national dignity, which is absolutely inviolable.

Yan Zi won this diplomatic victory with humility, courtesy and clear words. Safeguarded national dignity and personal dignity. Later, people also extracted the idiom "orange in the south and orange in the north" from Yan Zi's "orange in Huainan, orange in Huaibei". The ancients thought that oranges in the south would become bitter oranges when transplanted to the north of Huaihe River.