In A Little Red Among the Evergreens, "green" refers to a large green leaf, and "a little red" refers to a bright red flower. Metaphor highlights the most wonderful point among many things, which is enough to attract people's attention. From Wang Song Anshi's Ode to Pomegranate Flowers.

Idiom story:

According to legend, there is a story that an advanced examination of painting was held in the Song Dynasty, which brought together painters from all over the world. Mr. Evonne, the master of the emperor, wrote a question: "A little red in evergreen does not need much touching spring scenery." As a result, someone came first with a stroke of the pen. He painted a small building in the jungle. There was a beautiful woman upstairs by the window with a little lipstick on her lips.

China folk proverb says, "There is a little red in evergreen". Compared with "evergreen tree", red is more prominent and lovely, and because of this, the whole evergreen tree has a soul, just like the "introduction" of a piece of music.