The conduction of water is carried out by sapwood, which is the living part of the wood. Further if the sap wood is exposed freely in air, decomposition is rapid. Hence a plant dies if the sap wood is destroyed.

The climatic conditions remain same throughout the year in the seashore region. Thus distinct Annual rings are not formed.

(i) It is a poor conductor of heat.
(ii) Can be transported to long distances.
(iii) Wood is able to absorb vibrations and shock and used in making railway sleepers.
(iv) Does not show any rusty spots and tolerates compression, pull, bending etc.

The term 'bark' is commonly applied to all the tissues outside the vascular cambium of stem (i.e., periderm, cortex, primary phloem and secondary phloem).

Based on the arrangement of the fusiform initials, two types of vascular cambium are recognized. Storied (Stratified cambium) and Non-Storied (Nonstratified cambium)

(i) It is a resin obtained from bark of conifers.
(ii) It is used as thinner for oil based paints and organic solvents.

(a) Bark protects the plant from parasitic fungi and insects.
(b) It prevents water loss by evaporation and guards against variations of external temperature.
(c) It is an insect repellent, and is decay proof, fire proof.
(d) It is also a source of drugs and spices.

(i) Age of wood can be calculated.
(ii) Radio carbon dating can be verified.
(iii) Provides evidence in forensic investigation.

In a tree Additional growth rings are developed within a year due to adverse natural calamities like drought, frost, defoliation, flood, mechanical injury and biotic factors during the middle of a growing season, which results in the formation of more than one annual ring. Such rings are called pseudo-or false- annual rings.

(i) In winter season the cambium is less active and forms fewer xylary elements that have narrow vessels / tracheids and this is called Autumn wood or lat wood.
(ii) They are thick walled. Autumn wood is darker in colour and has a higher density. This is covered by spring wood.
(iii) Thus the center part of wood is always dark.

In the spring season, because cambium is very active and produces a large number of xylary elements having vessels / tracheids with wide lumen.

(i) If the bark of a tree is damaged by the horn of a deer, the tree first seals the damaged region from microbial infection.
(ii) This happens by altering the chemistry of the affected area by forming a callus, which grows and covers the damaged area.