What is the meaning of China's traditional "four old friends" and its origin?

The exact name is "Three Friends in Cold Age", which is an idiom in China. It comes from Lin Jingxi's "Mei She Ji Wu Yun" in the Song Dynasty: "If you live in a tired place, you will grow hundreds of plums, and you will be three friends in Cold Age with Qiao Song." Three friends old cold refers to pine, bamboo and plum; Pine and bamboo do not wither in winter; Plum blossoms in cold regions. These three plants are named after their tenacious vitality in the cold winter, and they are symbols of noble personality in China traditional culture. The so-called "four old friends" means that some people include "chrysanthemum". In fact, chrysanthemums in early winter are still very warm, because chrysanthemums also have tenacious vitality and are as noble as pine, bamboo and plum. But this was added by later generations. Whether it is recognized or not depends on personal treatment.