Three Friends of Winter / Steadfast, Loyal Friends
“Three friends of winter” refer to the pine, bamboo and plum. In traditional culture, certain human characteristics are attributed to plants and animals based on their natural qualities. The pine and bamboo remain green all year round even in the coldest season, and the plum blooms in early spring when snow and frost are still frequent. These three plants are cold resistant and retain their beauty even in harsh weather, just like good friends keep each other’s company during an icy winter. This term is often used to refer to loyal and steadfast friendship, and also represent the fine qualities of high-mindedness and detachment.
In the deadliest cold season, the pine and cedar are always the last to wither. (The Analects)
By late autumn, all the other flowers have withered. Only the pine, bamboo and plum remain vibrant, thus described as three steadfast friends in the cold. (Casual Talk Between a Fisherman and a Woodcutter)