Which organism lacks archegonium

Options

A. Funaria
B. Pteris
C. Spirogyra
D. Cycas.

Answer

### Step-by-Step Solution:

1. **Understanding Archegonium**:
- Archegonium is the female reproductive structure found in certain plants. It is responsible for producing the female gamete (egg).
- Organisms that possess archegonia are referred to as archegoniates.

2. **Identifying Plant Groups**:
- **Bryophytes**: These are non-vascular plants (like mosses) that have archegonia. They are considered archegoniates.
- **Pteridophytes**: This group includes ferns and their relatives, which also have archegonia, making them archegoniates.
- **Gymnosperms**: These are seed-producing plants (like conifers) that also possess archegonia, thus falling under archegoniates.

3. **Analyzing the Options**:
- The question provides three options: Phaneria, Teres, and Cycus.
- **Phaneria**: Belongs to Bryophytes, hence it has archegonia.
- **Teres**: A type of Pteridophyte, which also has archegonia.
- **Cycus**: A gymnosperm, which means it has archegonia as well.

4. **Identifying Non-Archegoniates**:
- Non-archegoniates are organisms that do not have archegonia. Examples include certain algae and angiosperms (flowering plants).
- Specifically, filamentous green algae like **Spirogyra** do not possess archegonia.

5. **Conclusion**:
- Since all the options provided (Phaneria, Teres, Cycus) are archegoniates, the organism that lacks archegonium is **Spirogyra**, which is a type of green algae.

### Final Answer:
**Spirogyra (a filamentous green alga) lacks archegonium.**

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