root-bark of tree peony

例句：

1. 1. The roots of the tree are deeply buried in the soil.
   这棵树的根深深地埋在土壤里。
2. 2. The root-bark is rich in nutrients that the plant needs to grow.
   树皮富含植物生长所需的养分。
3. 3.The roots-bark of the tree can be used as a natural fertilizer.
   树皮可以用作天然肥料。