In Riccia / Marchantia the rhizoids are

Options

A. Branched unicellular
B. Branched multicellular
C. Unbranched multicellular
D. Unbranched unicellular.

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question mentions Riccia and Marchantia, which are both types of bryophytes.

2. **Understand the Structure of Bryophytes**: Bryophytes have a thallus body structure, meaning they do not possess true roots, stems, or leaves. Instead, they have root-like structures called rhizoids.

3. **Examine the Thallus of Marchantia**: Marchantia has a dorsiventral thallus, which means it has distinct upper and lower surfaces. The upper surface has polygonal areas known as areolae, which contain air pores.

4. **Focus on the Rhizoids**: On the lower surface of the thallus, Marchantia has two types of unicellular rhizoids.

5. **Types of Rhizoids**:
- **Smooth-walled rhizoids**: These are responsible for anchoring the plant to the substrate.
- **Tuberculate rhizoids**: These are involved in conduction.

6. **Characteristics of Rhizoids**: Both types of rhizoids are unicellular and unbranched.

7. **Conclusion**: Therefore, the correct answer to the question is that in Riccia and Marchantia, the rhizoids are unicellular and unbranched.

### Final Answer:
The rhizoids in Riccia and Marchantia are unicellular and unbranched.

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