Red beans are the general name of seeds of mimosaceae plants, such as red beans and peacock beans. Among them, sea red beans are shiny and never fade, like a heart-shaped ruby. If you look closely, you will find that its red color gradually deepens from the edge to the inside, and the innermost particularly bright red part is heart-shaped. It is really a big heart, a heart. Therefore, jellyfish, also known as acacia beans, has always been regarded as a symbol and token of love and friendship.

It is also because of the poem of Tang Dynasty poet Wang Wei: "When those red berries come in spring, they bloom in your southern branches. Take them home for me as a symbol of our love." By love with red beans.

This poem is widely praised, so it has formed idioms similar to allusions.

Added is:

There is another legend. According to legend, there was a young woman in ancient times who died in frontier fortress because she missed her husband. She leaned against the tree in front of the door, crying day and night, and her tears dried up. Blood flowed out of her eyes, and blood and tears dyed her roots red, thus producing red beans with acacia significance. It's called locust bean.