True elaters and gemmae are concerned with:-

Options

A. Riccia
B. Marchantia
C. Anthoceros
D. Notothylus

Answer

To solve the question regarding true elaters and gemmae, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **True Elaters**: These are specialized structures found in certain plants, specifically in the class Hepaticopsida, which includes liverworts like Merchantia. They are elongated, spindle-shaped structures that assist in the dispersal of spores.
- **Gemmae**: These are asexual reproductive structures that can develop into a new organism. In the case of Merchantia, gemmae are produced for vegetative propagation.

2. **Identifying the Plant Group**:
- The question lists four options: Rixia, Merchantia, Anthoceros, and Notothilus.
- Among these, **Merchantia** is known to produce both true elaters and gemmae.

3. **Function of True Elaters**:
- True elaters are diploid structures that help in the dispersal of spores. They are hygroscopic, meaning they respond to moisture, which aids in the release of spores when conditions are favorable.

4. **Function of Gemmae**:
- Gemmae serve as vegetative propagules, allowing the plant to reproduce asexually. They can detach from the parent plant and grow into new individuals.

5. **Conclusion**:
- Both true elaters and gemmae are specifically associated with **Merchantia**, which is a member of the Hepaticopsida class of liverworts.

### Final Answer:
True elaters and gemmae are concerned with **Merchantia**.

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