"They don't usually grow back because when you cut down to the stump, you remove all meristematic tissue. Meristematic tissue is like stem cells in animals. They differentiate into different cells and allow the tree to have different types of cells, even 100 feet up high. The meristematic tissue is usually located at the very highest point where the tree is growing. In this way, the tree will always have the TYPES of cells it needs at all points in the tree. When you cut off the meristematic tissue, there are no cells to grow upward and differentiate themselves."