Spear Grass (Aristida) is dispersed by

Options

A. Air
B. Animals
C. Water
D. Explosive mechanism

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the mechanism of seed dispersal for Spear Grass, scientifically known as Aristida. We need to identify whether the seeds are dispersed by air, animals, water, or an explosive mechanism.

2. **Identifying Seed Dispersal Mechanisms**: There are several common mechanisms of seed dispersal:
- **Anemochory**: Dispersal by wind (air).
- **Zoochory**: Dispersal by animals.
- **Hydrochory**: Dispersal by water.
- **Autochory**: Dispersal by explosive mechanisms.

3. **Analyzing Aristida (Spear Grass)**:
- Aristida is known for its seeds that have stiff hair-like structures. These structures help the seeds attach to animals, facilitating their dispersal.
- The seeds of Aristida are often consumed by animals, which then excrete them far from the parent plant, allowing for wider distribution.

4. **Evaluating the Options**:
- **Air**: While some plants do disperse seeds via wind, this is not the case for Aristida.
- **Animals**: This is the correct answer as Aristida seeds are dispersed by animals (zoochory).
- **Water**: Aristida does not rely on water for seed dispersal.
- **Explosive Mechanism**: This is also incorrect for Aristida.

5. **Conclusion**: Based on the analysis, the correct answer is that Spear Grass (Aristida) is dispersed by animals.

**Final Answer**: B) Animals

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