Which of the following types of trees belong to the endogenous trees?
🌳 How Trees Grow: A Basic Classification
For engineering purposes, trees are classified into two main groups based on how their stems grow. This fundamental difference in growth pattern determines the internal structure of the wood and its suitability for construction.
📝 Detailed Analysis of the Options
(a) Deodar, (b) Pine, (c) Oak
These trees are all examples of Exogenous trees. These trees grow outwards, increasing in height and thickness simultaneously. Each year, they add a new layer of wood (an annual ring) just below the bark. This method of growth produces the strong, dense timber that is widely used in engineering works. Examples include Teak, Sheesham, Sal, Deodar, Pine, and Babul.
(d) Bamboo
This is the correct answer. Bamboo is a classic example of an Endogenous tree. These trees grow inwards. They grow in height but do not grow outwards in thickness by adding rings. Instead of distinct rings, long fibers emerge from within the trunk, which is typically long, thin, and flexible. Because their internal structure is a fibrous mass rather than solid wood, their use in major engineering works is nominal, though they are excellent for scaffolding and temporary structures. Other examples include Coconut, Palm, Dates, and Cane.
📊 Endogenous vs. Exogenous Trees
| Feature | Endogenous Trees | Exogenous Trees |
|---|---|---|
| Growth Pattern | Inward growth; grows in height but not thickness. | Outward growth; adds annual rings. |
| Internal Structure | Fibrous mass, long fibers. | Distinct pith, heartwood, sapwood, bark. |
| Engineering Use | Nominal (scaffolding, temporary use). | Primary source of structural timber. |
| Examples | Bamboo, Coconut, Palm, Cane. | Teak, Sal, Pine, Deodar, Oak. |
💡 Study Tips
- Endo = In: Remember that "Endo" means "within" or "inward." Endogenous trees grow by adding fibrous mass to their interior.
- Exo = Out: Remember that "Exo" means "outside." Exogenous trees grow by adding new layers to the outside, just under the bark.
- Bamboo is the Key: The most common example of an endogenous tree is bamboo. Its distinct, non-woody structure is easy to visualize.
- Rings = Exogenous: If a tree has annual rings, it is an exogenous tree. This is the source of almost all commercial timber.