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 "Stem with open vascular bundles arranged in a ring contains?", we need to analyze the structure of a dicot stem and identify the correct features associated with it.

### Step-by-Step Solution:

1. **Understanding Vascular Bundles**:
- In dicot stems, vascular bundles are arranged in a ring formation. This is a key characteristic that distinguishes dicots from monocots, where vascular bundles are scattered.

2. **Identifying Open Vascular Bundles**:
- Open vascular bundles contain both xylem and phloem, and they have the ability to form secondary growth. This means that they can contribute to the thickness of the stem over time.

3. **Examining the Components of the Dicot Stem**:
- The outermost layer of the stem is the epidermis, followed by the cortex, which includes several layers:
- **Hypodermis**: Composed of collenchyma cells that provide mechanical support.
- **Cortex**: Contains parenchyma cells.
- **Endodermis**: This layer is rich in starch granules and is often referred to as the starch sheath.

4. **Evaluating the Options**:
- **Option 1**: Water-containing cavities within the vascular bundle - This is incorrect as dicot stems do not have such cavities.
- **Option 2**: Large and well-developed pith with exarched and polyexarched xylem bundles - This is also incorrect because dicot stems typically have an endarch condition.
- **Option 3**: Endodermis rich in starch grains (starch sheath) - This is correct as the endodermis in dicot stems is indeed rich in starch granules.

5. **Conclusion**:
- The correct answer to the question is that a stem with open vascular bundles arranged in a ring contains an endodermis rich in starch grains, also known as the starch sheath.

### Final Answer:
A stem with open vascular bundles arranged in a ring contains an endodermis rich in starch grains (starch sheath).

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