Which of the following is correct with regard to monocot stem ?

Options

A. Monocot stem have a well-developed collenchymatous hypodermis.
B. The vascular bundles are surrounded by a sclerenchymatous bundle sheath .
C. The cortex is differentiated into endodermis and pericycle .
D. The vascular bundles are conjoint and open.

Answer

To solve the question regarding the characteristics of monocot stems, we will analyze the options provided and determine which statement is correct based on the characteristics of monocot stems.

### Step-by-Step Solution:

1. **Understanding Monocot Stems**:
- Monocot stems are derived from plants that have seeds with a single cotyledon. They exhibit specific structural features that differentiate them from dicot stems.

2. **Characteristics of Monocot Stems**:
- **Epidermis**: The epidermis is single-layered and lacks epidermal hairs.
- **Hypodermis**: The hypodermis is typically made of sclerenchyma (not collenchyma).
- **Ground Tissue**: The ground tissue in monocot stems is not differentiated into cortex and pith.
- **Vascular Bundles**: Vascular bundles in monocots are scattered throughout the stem and are surrounded by a sclerenchymatous bundle sheath. They are also typically closed (not open) and conjoined.

3. **Analyzing the Options**:
- **Option 1**: "Well-developed cholencymatous hypodermis" - This is incorrect, as the hypodermis in monocots is sclerenchymatous, not collenchymatous.
- **Option 2**: "Vascular bundles are surrounded by sclerencymatous bundle sheath" - This is correct.
- **Option 3**: "Cortex is differentiated into endodermis and pericycle" - This is incorrect; monocots do not have a distinct endodermis and pericycle.
- **Option 4**: "Vascular bundles are conjoined and open" - This is incorrect; vascular bundles are scattered and typically closed in monocots.

4. **Conclusion**:
- The only correct statement regarding monocot stems is that "vascular bundles are surrounded by sclerencymatous bundle sheath."

### Final Answer:
The correct option is: **"Vascular bundles are surrounded by sclerencymatous bundle sheath."**