Secondary growth occur in which pteridophyte

Options

A. Azolla
B. Salvinia
C. lsoetes
D. Selaginella

Answer

### Step-by-Step Solution:

1. **Understanding Secondary Growth**:
- Secondary growth refers to the increase in the girth or diameter of a plant, which is primarily due to the activity of the cambium, a type of lateral meristem.

2. **Types of Growth in Plants**:
- There are two main types of growth in plants:
- Primary growth, which results in an increase in length.
- Secondary growth, which results in an increase in girth.

3. **Characteristics of Pteridophytes**:
- Pteridophytes are a group of vascular plants that typically do not have cambium, which means they generally do not exhibit secondary growth.

4. **Identifying Exceptions**:
- While most pteridophytes do not show secondary growth, there is an exception.
- The genus **Isoetes** (commonly known as quillworts) is a type of pteridophyte that possesses cambium and can exhibit secondary growth.

5. **Conclusion**:
- Therefore, the answer to the question of which pteridophyte exhibits secondary growth is **Isoetes**.