Which of the following arrangements of xylem is observed in a stem ?

Options

A. Protoxylem lies towards pith in the centre
B. metaxylem lies towards the periphery of the organ
C. an endarch arrangement is present
D. All the above

Answer

To solve the question regarding the arrangement of xylem observed in a stem, we can break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Xylem Arrangement**:
- Xylem is a type of vascular tissue responsible for the transport of water and nutrients in plants. Its arrangement can vary between different plant organs, such as stems and roots.

2. **Identifying the Types of Xylem**:
- In dicot stems, xylem is typically arranged in a specific manner. It consists of protoxylem and metaxylem.

3. **Analyzing the Statements**:
- **Statement 1**: "Protoxylem lies towards the pith in the center."
- This statement is correct. In dicot stems, protoxylem is located closer to the center (pith) of the stem.

- **Statement 2**: "Metaxylem lies towards the periphery of the organ."
- This statement is also correct. In dicot stems, metaxylem is positioned towards the outer part of the stem, away from the pith.

- **Statement 3**: "An endarch arrangement is present."
- This statement is correct as well. In an endarch arrangement, the protoxylem develops from the innermost precambial cells, moving outward. This is typical in the development of xylem in stems.

4. **Conclusion**:
- Since all three statements regarding the arrangement of xylem in a stem are correct, the correct answer to the question is **Option 4**: All of the above.