pinenchyma

例句：

1. 1.The tree's bark is rough and tough.
   这棵树的树皮粗糙且坚韧。
2. 2.The sapwood of the tree is soft and easily damaged.
   这棵树的树心是柔软的，容易损坏。
3. 3.Heartwood is harder and more resistant to decay.
   心材更硬，对腐烂更有抵抗力。