1. The phellem is the outermost layer of bark on a tree.
树皮的最外层是薄皮组织。

2. The phellem helps protect the tree from pests and diseases.
薄皮组织有助于保护树木免受害虫和疾病的侵害。

3. The phellem is made up of dead cells that provide a barrier against external threats.
薄皮组织由死细胞组成，提供了一个屏障来防止外部威胁。

4. Damage to the phellem can weaken the tree and make it more susceptible to infection.
薄皮组织的损坏会削弱树木，使其更容易感染。

5. The phellem can vary in thickness depending on the species of tree.
薄皮组织的厚度会根据树种的不同而有所不同。

6. It is important to protect the phellem of a tree to ensure its health and longevity.
保护树木的薄皮组织对于确保其健康和长寿非常重要。