EVERYDAY SCIENCE

Detailed explanation-1: -heartwood, also called duramen, dead, central wood of trees. Its cells usually contain tannins or other substances that make it dark in colour and sometimes aromatic. Heartwood is mechanically strong, resistant to decay, and less easily penetrated by wood-preservative chemicals than other types of wood.

Detailed explanation-2: -Duramen is called the heartwood. After certain years of growth, the xylem elements of the stems of a number of trees develop dark brown coloration, especially in the central or innermost layers. This region comprises a dead element with highly lignified walls and is called heartwood or Duramen.

Detailed explanation-3: -sapwood, also called alburnum, outer, living layers of the secondary wood of trees, which engage in transport of water and minerals to the crown of the tree. The cells therefore contain more water and lack the deposits of darkly staining chemical substances commonly found in heartwood.

Detailed explanation-4: -As the tree ages, certain permanent changes take place in the wood. The inner parts of the wood become darker. The xylem in this central part is called heartwood or ‘duramen’. The peripheral part of the wood is light coloured and it is called sapwood or ‘alburnum’.

Detailed explanation-5: -(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.