Why the colour of heart wood is dark ?

Explanation

### Step-by-Step Solution:

1. **Understanding Heartwood and Sapwood**:
- Heartwood is the central, non-living part of a tree trunk, while sapwood is the outer, living layer that transports water and nutrients.
- As a tree matures, the inner layers of sapwood become heartwood.

2. **Formation of Heartwood**:
- Over time, the sapwood eventually dies and stops functioning in the transportation of water and nutrients.
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