Instead of elaters, the sporogonium of Riccia contains

Options

A. Nurse cells
B. Pseudoelaters
C. Photosynthetic cells
D. Columella.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks what replaces elaters in the sporogonium of Riccia. Elaters are specialized structures found in some bryophytes that assist in the dispersal of spores.

2. **Identifying Elaters**: Elaters are tubular cells with spiral thickenings that help in the release of spores. They are typically found in certain bryophytes, such as Marchantia.

3. **Examining Riccia**: Riccia is a genus of liverworts, which is a type of bryophyte. Unlike some other bryophytes, Riccia does not have elaters in its sporogonium.

4. **Exploring the Options**:
- **Nurse Cells**: These are specialized cells that provide nourishment to the developing spores in Riccia. They take the place of elaters in the sporogonium.
- **Pseudo Elaters**: These are similar to elaters but are not found in Riccia.
- **Photosynthetic Cells**: These cells are involved in photosynthesis but do not serve the same function as elaters.
- **Columella**: This is a structure found in the sporangium of some plants, but it does not replace elaters in Riccia.

5. **Conclusion**: The correct answer is that instead of elaters, the sporogonium of Riccia contains **nurse cells**.

**Final Answer**: Nurse cells.

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