Explain the difference between heartwood and sapwood.

(N/A) $\Rightarrow$ Heartwood: In old trees,the greater part of secondary xylem is dark brown due to the deposition of organic compounds like tannins,resins,oils,gums,aromatic substances,and essential oils in the central or innermost layers of the stem. These substances make it hard,durable,and resistant to the attacks of microorganisms and insects. This region comprises dead elements with highly lignified walls and is called heartwood. Heartwood does not conduct water but provides mechanical support to the tree.
$\Rightarrow$ Sapwood: The peripheral region of secondary xylem is lighter in color and is known as sapwood. It is involved in the conduction of water and minerals from the root to the leaves.