What are achenial fruits ?

Explanation

### Step-by-Step Text Solution:

1. **Definition of Achenial Fruits**: Achenial fruits are a type of dry fruit that is characterized by having a single seed. They are classified as indehiscent fruits, meaning they do not open to release their seeds when they mature.

2. **Characteristics of Achenial Fruits**:
- **Single Seed**: Each achene contains only one seed.
- **Dry Nature**: Achenes are dry fruits, which means they do not have a fleshy outer layer.
- **Indehiscent**: Achenes do not split open at maturity to release their seeds. They remain closed even when they are fully mature.
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