Answer the following question given this paragraph: 

In trees, some of the epidermal tissue is replaced by bark. Bark is a combination of tissues that provides a tough, woody external covering on the stems of trees. The inner part of bark is alive and growing; the outer part is dead and provides strength, support, and protection.


Q: What is the combination of tissues that provides a tough, woody external covering on the stems of trees called?


A:
bark