Tree trunks are the main support structure of a tree, connecting the roots to the branches and leaves. They are typically cylindrical and made up of several layers, including the bark, cambium, xylem, and phloem. The bark protects the tree from pests and environmental damage, while the xylem transports water and nutrients from the roots to the leaves. The thickness and height of a tree trunk can vary greatly depending on the species of the tree and its environment. Some common types of trees with notable trunks include oak, pine, and maple. A healthy trunk is essential for the overall growth and stability of the tree.