heart wood differs from sapwood in

Options

A. being susceptible ot pests and pathogens
B. presence of rays and fibres
C. absence vesselsand prenchyma
D. having dead and non-conducting elements

Answer

### Step-by-Step Solution:

1. **Definition of Heartwood and Sapwood**:
- Heartwood is the central, non-living part of a tree trunk, composed primarily of dead xylem. It provides structural support and is often darker in color due to the accumulation of various substances.
- Sapwood, on the other hand, is the outer layer of the xylem that is still alive and functional. It is lighter in color and is responsible for the conduction of water and nutrients.

2. **Composition**:
- Heartwood consists of dead xylem vessels that are filled with substances like tyloses, resins, and tannins. These substances contribute to its darker appearance and non-conducting nature.
- Sapwood contains newly formed xylem vessels that are functional and actively involved in the transport of water and nutrients.

3. **Functional Differences**:
- Heartwood is non-functional in terms of water conduction; it does not transport water or nutrients. Its primary role is to provide strength and stability to the tree.
- Sapwood is functional and plays a crucial role in the tree's physiology by conducting water and nutrients from the roots to the leaves.

4. **Presence of Elements**:
- Heartwood is characterized by the presence of dead and non-conducting elements, which is a key distinguishing factor from sapwood.
- Sapwood, in contrast, contains living cells and is composed of functional elements.

5. **Conclusion**:
- Based on the differences outlined, the correct answer to the question "Heartwood differs from sapwood in" is **Option D: having dead and non-conducting elements**.