Elm tree.
Locust trees, willow trees, and elm trees: "auspicious trees" in the eyes of the ancients. According to ancient records, locust trees, willow trees, elm trees, and sycamore trees were the most favored by the ancients. These trees are not only very common, but they are also not precious species. So why did the ancients like them so much? It turns out that they all have special symbols and are all "auspicious trees" in the eyes of the ancients. Sophora japonica: It has been officially selected as a greening tree species in the pre-Qin Dynasty. As the saying goes: "If you have a sophora japonica in front of your door, you will get promoted and make a fortune." Judging from the planting history, the sophora japonica tree has been one of the officially selected greening tree species as early as the pre-Qin Dynasty. According to the "Court Scholars" article in "Zhou Li Qiu Guan", the king of Zhou's courtyard has the sayings of "nine thorns on the left", "nine thorns on the right" and "three locust trees on the face". This means that 9 thorn trees are planted on the left and right, and 3 locust trees are planted on the south.