In cells of endothecium, a cellulosic fibrous bands arise from
(a) Outer radial wall
(b) Inner tangential wall
(c) Outer tangential wall
(d) Both on inner and outer tangential walls

Options

A. Outer radial wall
B. Inner tangential wall
C. Outer tangential wall
D. Both on inner and outer tangential walls

Answer

To solve the question regarding the origin of cellulosic fibrous bands in the cells of endothecium, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Endothecium**:
- The endothecium is a layer of cells located beneath the epidermis of the anther in flowering plants. It plays a crucial role during the development of pollen grains.

**Hint**: Remember that the endothecium is part of the anther structure.

2. **Identifying Cell Structure**:
- The cells of the endothecium are elongated and have specific structural features that contribute to their function.

**Hint**: Focus on the characteristics of the endothecium cells.

3. **Fibrous Thickening Composition**:
- The fibrous bands that arise in these cells are primarily made up of alpha cellulose, along with traces of pectin and lignin.

**Hint**: Consider what materials make up the fibrous thickenings.

4. **Location of Fibrous Bands**:
- The question asks where these cellulosic fibrous bands arise from. According to the information, these thickenings develop from the inner tangential wall of the endothecium cells.

**Hint**: Pay attention to the specific walls of the cells mentioned in the options.

5. **Choosing the Correct Option**:
- Based on the understanding that the fibrous thickenings arise from the inner tangential wall, the correct answer is option (b) inner tangential wall.

**Hint**: Verify which option corresponds to the inner tangential wall.

### Final Answer:
(b) Inner tangential wall