Question

Which option is true about heart wood/duramen?
(i) It does not help in water and mineral conduction.
(ii) It is dark colored but soft.
(iii) It has tracheary elements filled with tannins, resins, gums, oil, etc.
(iv) It is a peripheral part.
(v) Sensitive to microbes and insects, hence least durable.

• A. (i) and (iii)
• B. (ii) and (iii)
• C. (iv) and (v)
• D. (iii) and (iv)

Answer 1

The correct option is A (i) and (iii)

• Heart wood (duramen) is the central wood of an old stem. It is dark colored. Living cells are absent. Heart wood is the part of secondary xylem.
• The tracheary elements are plugged by tyloses. Tracheary elements have deposition of tannins, resins, gums, etc. Heart wood is heavier. It is more durable due to its little susceptibility to the attack of pathogens and insects. Heart wood is mechanical in function.
• The outer or peripheral portion of the trunk is lighter in color and soft which performs the functions of conduction of water and minerals and it is known as sap wood or alburnum.