What techniques are used in Autumn in the Old Capital to describe the fruit trees in the north?

Autumn in the old capital describes the fruit trees in the north with clause structure. It depicts the plainness of autumn in the south and hints at the beauty of autumn in the north. Later, the author began to describe autumn in the north, and one of them was about fruit trees in autumn. There is a saying: "Like olives and pigeon eggs, this jujube shows a light green and yellowish color among the small oval leaves.