What are the cultural traditions of clouds, golden willows and green grass in classical poetry?

"Clouds, golden willows and green grass" are three distinct images in Xu Zhimo's Biekang Bridge. In the traditional culture of China, these three images condensed a heavy human emotion-the feeling of parting.

Cloud: "I will think of you in a floating cloud", "This cloud that has been floating in the sky all day may be like a wanderer and never come back", "Life is like a floating cloud". Floating clouds have no roots and float with the wind. This is the image of a wandering wanderer.

"Liu" and "Liu" are homonyms, and the ancients had the cultural custom of breaking the willow to bid farewell. "The Golden Willow by the River is the Bride in the Sunset", although it is another village with a bright future, but the artistic conception is refurbished, unlike "ecstasy is just parting", in which beauty is more than sadness.

Green grass: "The courtyard is as empty as water, and the algae in the water are intertwined, and the bamboo and cypress are hidden." "Linghuateng follows the sculls" and "seaweed lingers around, like nostalgia and flying in a gull bath." "The lake is flat and the water is lingering at the stern." In the image of green grass, there is a lingering meaning, although "I want to stay in spring."