Orthotropous ovules occur in

Options

A. Pisum sativum
B. Solanum nigrum
C. Polygonum
D. Helianthus.

Answer

### Step-by-Step Solution:

1. **Understanding Orthotropous Ovules**:
- Begin by defining what an orthotropous ovule is. It is the simplest and most primitive type of ovule where the ovule, micropyle, chalaza, and funiculus are aligned in a single vertical plane.

2. **Identifying Characteristics**:
- Note the key characteristics of orthotropous ovules:
- All parts (ovule, micropyle, chalaza, funiculus) are in one vertical plane.
- This type of ovule is primarily found in gymnosperms.

3. **Analyzing the Options**:
- Look at the given options:
- Piezonsatavum
- Solanum negrum
- Polygolum
- Helianthus
- Identify which of these is a gymnosperm, as orthotropous ovules are mainly found in this group.

4. **Identifying the Correct Answer**:
- Among the options, Polygolum (likely referring to Polygonum) is known to contain orthotropous ovules. The other options are not primarily associated with orthotropous ovules.

5. **Final Conclusion**:
- Therefore, the correct answer to the question "Orthotropous ovules occur in" is **Polygolum**.