Sophora japonica, also known as Sophora japonica, has a thick and straight trunk, pinnately compound leaves, yellow-white flowers and a butterfly-shaped corolla (5 petals, the largest 1 above is called the flag petal; The two petals on both sides are called wing petals, and the lower two petals are called keel petals. The corolla is shaped like a butterfly, and the stamens 10 are separated. The fruit is a pod in the shape of a rosary. Sophora japonica is a native of our country. It was often planted in palaces or temples in ancient times. It was called "Palace Sophora japonica" in ancient books.

Another kind of Sophora japonica, Robinia pseudoacacia, is different from Sophora japonica, and looks similar to Sophora japonica. The bark of young branches is grayish brown, with deep grooves on the skin and thorns on the branches. The flowers are milky white, and the clusters are large and drooping, with fragrant smell. Stamens 10, 9 of which are combined into a bundle, and the other one is separated separately, which we call diploid stamens; Pods are flat and wide, native to North America. It is said that Robinia pseudoacacia was introduced to China around 1900, and first settled in Qingdao, so it has a history of about 100 years. Robinia pseudoacacia grows and reproduces rapidly. At the beginning, there were many Robinia pseudoacacia in Qingdao, so some people called it "Robinia pseudoacacia Island", and later it was widely planted in various places. The trunk wood of Robinia pseudoacacia is solid, elastic and corrosion-resistant, and it is a good material for vehicles, pillars and sleepers. In the north, it is often used as a street tree or as an afforestation tree, planted on barren hills.