Question

Heart wood is:

• A. Central part of secondary xylem
• B. Peripheral part of secondary xylem
• C. Central part of secondary phloem
• D. Peripheral part of secondary phloem

Answer 1

The correct option is A Central part of secondary xylem

During secondary growth the materials such as tannin, resin, gums, oil, phenols and aromatic substances, etc. are filled in lumen of tracheids and vessels of secondary xylem. Due to this, central region of secondary xylem becomes dark brown. It is called heartwood.