The bark that covers the tree trunk helps protect the transport of these nutrients. The tree's bark is its skin. It protects the tree from animals, and from drying out. Buds of trees contain very small leaves folded inside a case. Once these small leaves burst out of the case, the leaves get larger, and unfold.
Leaves get energy from sunlight.
They use this energy to carbon dioxide and water into fuel for the tree. There are several types of leaves. There are broad-leafed trees. These trees have either simple or compound types of leaves. Simple leaves have one main leaf, whereas compound leaves are a group of leaves attached to one stalk.