Which of the following wall layer anther shows fibrous thickening (of callose)

Options

A. Epidermis
B. Tapetum
C. Middle layer
D. Endothecium.

Explanation

To solve the question regarding which wall layer of the anther shows fibrous thickening of callose, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Anther**:
- The anther is a part of the male reproductive organ of flowering plants. It is typically bilobed and contains pollen sacs where pollen grains develop.

2. **Identify the Layers of the Anther**:
- The anther has four main layers:
- **Epidermis**: The outermost layer.
- **Endothesium**: The layer beneath the epidermis.
- **Middle Layer**: Located between the endothesium and the tapetum.
- **Tapetum**: The innermost layer, which provides nourishment to the developing pollen grains.

3. **Focus on the Function of Each Layer**:
- Each layer has specific roles. The tapetum is primarily nutritive, while the endothesium plays a significant role during the dehiscence (the process of opening to release pollen).

4. **Identify the Layer with Callose Thickening**:
- During the process of dehiscence, the endothesium produces fibrous thickening made of callose. This thickening is essential for the proper dispersal of pollen grains.

5. **Conclude with the Correct Answer**:
- Based on the information, the wall layer of the anther that shows fibrous thickening of callose is the **Endothesium**.

### Final Answer:
The correct answer is **Endothesium**.

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