In the second grade, winter vacation homework was cold, three friends were frosty and snowy, and his tree withered. What are pines, bamboos and plums at this time?

They are pine trees, bamboo and plums.

Pine, bamboo and plum are collectively called "three-year-old cold friends" These three plants are named after their tenacious vitality in the cold winter. They are symbols of noble personality in China traditional culture and metaphors of loyalty and friendship.

Three Friends in Cold and Summer is a seven-line quatrain poem by the poet Bai Yang. It consists of three poems: Song, Zhu and Mei.