In early summer, the ancient locust trees in Guozijianli were mostly planted in the Yuan Dynasty, more than 700 years ago. The famous "Recovery Sophora japonica" was planted in the Yuan Dynasty, on the west side of the Yiluntang. Legend has it that this locust died in the late Ming Dynasty, but in the early summer of the 16th year of the Qianlong reign of the Qing Dynasty, new buds and leaves sprouted on its branches, withered and rejuvenated. When the teachers and students of Guozijian found out, they began to praise it. It was the sixtieth birthday of Empress Dowager Cining, Qianlong's mother. People thought it was a good omen, so it was named "lucky Huai". There is also a "Luoguo Huai" beside the round pool in the west of Piyong Palace. Its trunk is in the shape of a Luo pot, with its upper part inclined to the south. The Luo pot on the north side of the trunk still has scars like those cut with sharp tools. It is said that Qianlong ordered people to cut off a large branch. The Piyong Palace was a place where the Emperor gave lectures. It was built under the chairmanship of Liu Yong, a scholar and supervisor of the state. The legend of Luo Guohuai is related to Liu Yong.