In old trees, central dark coloured, non-conducting part of secondary xylem is referred to as

Options

A. heartwood
B. sapwood
C. softwood
D. hardwood

Answer

A

Explanation

Heartwood (duramen) is the central wood of an old stem. It is dark coloured part of secondary xylem. Living cells are absent here. The tracheary elements are plugged by tyloses and have deposition of tannins, resins, gum, etc. heartwood is heavier. It is more durable due to its little susceptibility to the attack of pathogens and insects. the outer or peripheral portion of the trunk is soft and lighter in colour. it performs the function of conduction of water and minerals and is known as sapwook or alburnum.