Heterospory and origin of seed habit was noticed for the first time in :-

Options

A. Isoetes
B. Lycopodium
C. Selaginella
D. Dryopteris

Answer

To solve the question regarding where heterospory and the origin of seed habit was first noticed, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Heterospory**:
- Heterospory refers to the production of two different types of spores: microspores (smaller, male spores) and megaspores (larger, female spores). This is in contrast to homospory, where only one type of spore is produced.

2. **Identifying the Group of Plants**:
- Heterospory is primarily observed in certain groups of plants, particularly in pteridophytes (ferns and their relatives).

3. **Recognizing the Significance of Heterospory**:
- The evolution of heterospory is significant as it is a precursor to the development of seeds. The presence of both microspores and megaspores allows for more complex reproductive strategies.

4. **Paleobotanical Evidence**:
- Paleobotanical studies and developmental research suggest that heterospory arose due to the degeneration of spores in some sporangia, leading to an increase in the size of the surviving spores.

5. **Identifying Heterosporous Genera**:
- There are nine known genera of pteridophytes that exhibit heterospory. These include:
- Selaginella
- Isoetes
- Stauropus
- Marsilea
- Pilularia
- Salvinia
- Azolla
- Platyzoma

6. **Determining the First Instance of Heterospory**:
- Among these genera, Selaginella is recognized as the first instance where heterospory was observed.

7. **Conclusion**:
- Based on the information gathered, the correct answer to the question is that heterospory and the origin of seed habit were first noticed in **Selaginella**.

### Final Answer:
The correct option is **Selaginella**.