The dark inner wood that provides support is called?

• A. Heartwood
• B. Sapwood
• C. Xylem
• D. Phloem

Answer: (A)

Heartwood is the dark inner wood that provides structural support. As a tree ages, the center of the trunk becomes heartwood, filled with extracts like tannins and resins that darken the wood and help resist decay. It no longer conducts water. The layer around it, the sapwood, stays lighter in color and remains active in transporting water up from the roots. Xylem is the tissue that carries water and includes both heartwood (non-conducting) and sapwood (conducting). Phloem is the tissue in the outer bark that moves sugars throughout the tree. So the dark inner wood that provides support is heartwood.