Spring wood and Autumn wood are found in

Options

A. Sapwood
B. Phellogen
C. Heartwood
D. both 1 & 3

Answer

**Step-by-Step Solution:**

1. **Understanding Spring Wood and Autumn Wood**:
- Spring wood, also known as early wood, is produced during the growing season, typically in spring and early summer when conditions are favorable for growth.
- Autumn wood, also known as late wood, is produced later in the growing season, usually in late summer and autumn when growth slows down due to less favorable conditions.

2. **Formation of Growth Rings**:
- Both spring wood and autumn wood contribute to the formation of annual growth rings in trees. Each year, a new layer of wood is added, which consists of one layer of spring wood and one layer of autumn wood.

3. **Location of Spring Wood and Autumn Wood**:
- These types of wood are found in the secondary xylem of the plant, which is produced by the vascular cambium. The vascular cambium is responsible for the secondary growth in plants.

4. **Identifying the Correct Answer**:
- The question asks where spring wood and autumn wood are found. The correct answer is the vascular cambium, which is often referred to as phellogen in some contexts, but it is important to note that phellogen specifically refers to the cork cambium.

5. **Conclusion**:
- Therefore, spring wood and autumn wood are found in the vascular cambium, which is responsible for the production of secondary xylem and contributes to the growth rings of trees.

**Final Answer**: Spring wood and autumn wood are found in the vascular cambium.

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