Question

Heart wood of most of the woody trees, fails to conduct sap due to the obstruction by

• A. Excess secondary wall deposition
• B. Storing a variety of material by tyloses
• C. Deposition of reserved food material
• D. None of the above

Answer 1

The correct option is B Storing a variety of material by tyloses

Heart wood of most of the woody trees, fails to conduct sap due to the obstruction by tyloses. Tyloses are found in secondary xylem. They are outgrowths on parenchyma cells of xylem vessels. When the plant is stressed by drought or infection, tyloses will fall from the sides of the cells and dam up the vascular tissue to prevent further damage to the plant. Tyloses can aid in the process of making sapwood into heartwood in some hardwood trees, especially in trees with larger vessels. These blockages can be used in addition to gum plugs as soon as vessels become filled with air bubbles and they help to form a stronger heartwood by slowing the progress of rot.