Heartwood is characterised by all, except

Options

A. Presence of tyloses
B. Presence of tannins, resins, oils, gums etc.
C. Its commercial importance for timber
D. Active in water conduction

Answer

### Step-by-Step Solution:

1. **Understanding Heartwood**: Heartwood is the central, supporting pillar of a tree, typically darker and denser than the outer layers of wood. It is formed from the accumulation of secondary xylem over time.

2. **Characteristics of Heartwood**:
- **Presence of Tyloses**: Tyloses are outgrowths from the parenchyma cells that can block the vessels in the heartwood, contributing to its durability and resistance to decay.
- **Presence of Tannins**: Tannins are phenolic compounds that provide protection against herbivores and pathogens, contributing to the heartwood's dark color.
- **Presence of Resins, Oils, and Gums**: These substances also contribute to the heartwood's durability, making it less susceptible to decay and enhancing its commercial value.

3. **Commercial Importance**: Heartwood is commercially important as it is used in timber production due to its strength and aesthetic qualities. It is often used in furniture, flooring, and other applications where durability is essential.

4. **Water Conduction**: Heartwood is generally not active in water conduction. This function is primarily performed by the outer layer known as sapwood, which is lighter and softer.

5. **Conclusion**: The characteristic features of heartwood include the presence of tyloses, tannins, resins, oils, and gums. However, the statement that heartwood is active in water conduction is incorrect. Therefore, the answer to the question "Heartwood is characterised by all, except" would be its activity in water conduction.

### Final Answer:
Heartwood is characterized by all, except its activity in water conduction.

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