WOOD PARTS AND ANATOMY Taking a Look at Wood Heartwood and Sapwood If you look at the cross-section of a tree trunk, many times you'll see a dark, inner region, called the heartwood and a lighter, outer region called the sapwood. The sapwood is live wood and its main job is to carry water from the roots to other parts of the tree. The heartwood is dead wood, but it used to be live sapwood! The heartwood's main job is to provide support for the tree. Heartwood also helps the tree by being resistant to insect attacks and decay. So, if heartwood used to be sapwood... What happened?

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