They also contain the growing layer of the tree that makes the trunk, branches, and roots of the tree thicker each year. A Heartwood forms the central core of the tree, is made up of dense dead wood, and provides strength for the tree. Roots A tree's roots help anchor the tree in the ground. They also absorb water and nutrients from the soil. Trees have lateral roots that spread out from the tree and cover a broad area.
Many trees also have a taproot that grows straight into the ground.
As a tree's taproot and lateral roots grow away from the tree, they branch into finer and finer roots called rootlets. The rootlets themselves are, in turn, covered by even finer root hairs . These root hairs absorb approximately 95 percent of the water and nutrients absorbed by the tree. Then find a large, open area where the students can build the tree. Doing the Activity 1 .