At the time of anther dehiscence

Options

A. Middle layers develop fibrous thickenings
B. Epidermic degenerates
C. Endothecium develops fibrous thickenings
D. Endothecium degenerates.

Answer

### Step-by-Step Solution:

1. **Understanding Anther Structure**: The anther is a part of the stamen in flowering plants and is responsible for producing pollen. It consists of four layers: epidermis, endothelium, middle layer, and tapetum.

2. **Focus on Endothelium**: Among these layers, the endothelium plays a crucial role during anther dehiscence (the process where the anther opens to release pollen).

3. **Characteristics of Endothelium**: The cells of the endothelium are radially elongated and develop fibrous thickenings. These thickenings occur on the inner tangential walls of the cells.

4. **Composition of Fibrous Thickening**: The fibrous thickenings are primarily made up of alpha cellulose and contain traces of lignin. This composition is important for providing structural support.

5. **Functionality During Dehiscence**: As the anther matures, the hygroscopic nature of the endothelium allows it to expand. The outer tangential walls of the endothelium remain thin, which facilitates the opening of the anther.

6. **Conclusion**: Therefore, the correct statement regarding anther dehiscence is that "the endothelium develops fibrous thickening."

### Final Answer:
The correct option is: **Endothelium develops fibrous thickening.**

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