The yellow or brown spots which have sporangia in ferns are called ……….. .

Answer

**Step-by-Step Solution:**

1. **Identify the Structures in Ferns**: In ferns, the leaves are referred to as fronds. These fronds can have distinct spots on them.

2. **Recognize the Spots**: The yellow or brown spots observed on the fronds of ferns are actually clusters of sporangia.

3. **Define Sporangia**: Sporangia are reproductive structures that produce spores. In ferns, these are found on the upper surface of the fronds.

4. **Terminology**: The specific term used for these yellow or brown spots that contain sporangia is "sori" (singular: "sorus").

5. **Conclusion**: Therefore, the yellow or brown spots which have sporangia in ferns are called "sori" or "sorus".

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