Sex organs are embedded in the thallus in

Options

A. Moss
B. Riccia
C. Azolla
D. Fern.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism has sex organs embedded in the thallus. The options provided are morph, rixia, azola, and spurn.

2. **Identifying the Organism**: Among the options, we need to identify which one is known for having sex organs embedded in its thallus.

3. **Analyzing the Options**:
- **Morph**: This is not a recognized organism in the context of thallus and sex organs.
- **Rixia**: This is a genus of liverworts, which are known to have sex organs embedded in their thallus.
- **Azola**: This is a genus of ferns, which do not have sex organs embedded in the thallus.
- **Spurn**: This is not a recognized organism in the context of thallus and sex organs.

4. **Confirming Rixia**: In Rixia, the male sex organ (antheridia) is embedded in the thallus, specifically in an antherial chamber on the dorsal side. The female sex organ (archegonia) is also linked to the thallus by a stalk.

5. **Conclusion**: Based on the analysis, the correct answer is that sex organs are embedded in the thallus in **Rixia**.

**Final Answer**: Rixia

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