Heart wood is the

Options

A. outer part of secondary xylem
B. inner part of secondary xyloem
C. outer part of secondary phloem
D. inner part of secondary phloem

Answer

**Step-by-Step Solution:**

1. **Understanding Heartwood**: Heartwood is a term used to describe a specific type of wood found in trees. It is important to differentiate it from other types of wood, particularly sapwood.

2. **Identifying the Location**: Heartwood is located in the inner part of the tree's structure. It is formed from the secondary xylem during the secondary growth phase of a dicot stem.

3. **Characteristics of Heartwood**: Heartwood is characterized by its dark color and non-functional nature. This means that while it provides structural support to the tree, it does not play a role in the transport of water and nutrients.

4. **Comparison with Other Options**:
- Option A refers to the outer part of secondary xylem, which is known as sapwood.
- Option C refers to the outer part of secondary phloem, which is not related to heartwood.
- Option D refers to the inner part of secondary phloem, which is also not related to heartwood.

5. **Conclusion**: Based on the definition and characteristics of heartwood, the correct answer is that heartwood is the inner part of secondary xylem.

**Final Answer**: Heartwood is the inner part of secondary xylem (Option B).

---