Stem with open vascular bundles arranged in ring contains

Options

A. Water containing cavities within the vascular bundle
B. Large and well developed pith with exarch and polyarch xylem bundles
C. Vascular bundles surrounded by a layer of thick walled bundle sheath cells
D. Endodermis rich in starch grains and the layer is also referred to as starch sheath

Answer

To answer the question about what a stem with open vascular bundles arranged in a ring contains, we can break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Vascular Bundles**:
- Vascular bundles are structures that contain xylem and phloem, which are responsible for the transport of water, nutrients, and food in plants.

2. **Identifying Open Vascular Bundles**:
- Open vascular bundles have the ability to form secondary growth, which is a characteristic of dicotyledonous plants (dicots). This means that the vascular bundles are not completely surrounded by sclerenchyma, allowing for growth in thickness.

3. **Arrangement in a Ring**:
- In dicot stems, the vascular bundles are typically arranged in a ring formation. This arrangement is crucial for the growth and development of the plant.

4. **Components of Dicot Stem**:
- The stem consists of several layers:
- **Epidermis**: The outer protective layer.
- **Cortex**: Located beneath the epidermis, which includes:
- **Hypodermis**: The outermost layer of the cortex, made of collenchyma cells.
- **Cortical Layers**: Made up of parenchyma cells.
- **Endodermis**: The innermost layer of the cortex, which is rich in starch grains and is also referred to as the starch sheath.

5. **Endodermis**:
- The endodermis is significant because it regulates the movement of water and nutrients into the vascular system. The presence of starch grains in the endodermis indicates its role in storage.

6. **Conclusion**:
- Therefore, a stem with open vascular bundles arranged in a ring contains an endodermis that is rich in starch grains, which is also referred to as the starch sheath.

### Final Answer:
A stem with open vascular bundles arranged in a ring contains an endodermis rich in starch grains, also known as the starch sheath.

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