In cross-sectioned root form 2 middle bark layer next Internal bark layer especial structure of regularly array;

根横切面上形成了在紧靠内皮层的两层中皮层细胞有规则整齐排列成两环的特殊结构；

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If you peel birch bark in the winter, we call it "the winter bark", another layer, a tougher inner layer of the tree adheres to the bark, producing a stronger material.

如果你在冬天剥桦树皮，我们称它为“冬树皮”，另外一层更加坚硬的紧贴树皮的树层就可以生产出更强更硬的材料。

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The birch tree has white bark, and this tough protective outer layer of the tree, this white bark, is waterproof.

桦树有白色的树皮，树上这个坚硬的保护外层，这个白色的树皮，是防水的。

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