The stomatal apparatus includes -

Options

A. Only stomatal aperture
B. Stomatal aperture and guard cells
C. Only guard cells
D. Stomatal aperture, guard cells and surrounding subsidiary cells

Answer

To answer the question regarding the components of the stomatal apparatus, we can break down the information step by step.

### Step-by-Step Solution:

1. **Understanding the Stomatal Apparatus**: The stomatal apparatus is a structure found in the epidermis of leaves and stems that facilitates gas exchange. It primarily consists of various components that work together to regulate the opening and closing of stomata.

2. **Identifying the Main Components**:
- **Stomatal Pore**: This is the opening that allows gases (like CO2 and O2) to enter and exit the leaf.
- **Guard Cells**: These are specialized cells that surround the stomatal pore. They control the size of the pore by changing shape, thus regulating gas exchange and water loss.
- **Subsidiary Cells**: These are the cells that are located adjacent to the guard cells. They provide support and may assist in the functioning of the guard cells.

3. **Distinguishing Between Components**:
- The **guard cells** are specifically responsible for the opening and closing of the stomatal pore.
- The **subsidiary cells** help in the functioning of guard cells but are not directly involved in the gas exchange process.
- The **epidermal cells** are present on the outer layer but are not considered part of the stomatal apparatus itself.

4. **Conclusion**: Based on the components identified, the stomatal apparatus includes the stomatal pore, guard cells, and subsidiary cells. Therefore, the correct answer to the question is that the stomatal apparatus includes both the guard cells and the stomatal pore.

### Final Answer:
The stomatal apparatus includes the stomatal pore, guard cells, and subsidiary cells.