Classification Based on Mode of Growth: On the basis of mode of growth trees are classified as (a) Exogeneous and (b) Endogeneous

(a) Exogeneous Trees: These trees grow outward by adding distinct consecutive ring  in every year. These rings are called as annual rings. Therefore it is possible to find the age of timber by counting these annual rings. These trees can be further divided into

(1) coniferrous and

(2) deciduous.

Coniferrous trees consists cone shaped leaves and fruits. The leaves do not fall until new ones are grown. They yield soft wood.

Deciduous trees have broad leaves. In autumn these leaves fall and new ones appear in springs. They yield strong wood and therefore they are commonly utilized in building construction.

(b) Endogeneous Trees: These trees grow inwards. Fresh fibrous mass is in the inner most portions. Instance of endogenous trees are cane and bamboo. They are unuseful for structural works.