Sentence:  Every morning early , in the summer , we searched the trunks of the trees as high as we could reach for the locust shells , carefully detached their hooked claws from the <WSD>bark</WSD> where they hung , and stabled them , a weird faery herd , in an angle between the high roots of the tulip tree , where no grass grew in the dense shade . 
Meaning of the word marked with <WSD> tags:  tough protective covering of the woody stems and roots of trees and other woody plants