22. Phloem

This image shows the Phloem layer of a tree. The phloem is the part of the tree where sugars and other products are transferred from the leaves down the tree. The Red Oak pictured here is especially good at illustrating this function, as it has large, visible straws in its phloem.

 In the timber industry, it is commonly said that you can not make a barrel out of red oak, as it will leak, as a result of the large tubes in its phloem.