What are the characteristics of Equisetum (horsetails)? Why it is also called scouring rushes ?

Explanation

### Step-by-Step Solution:

1. **Definition of Equisetum**: Equisetum, commonly known as horsetails, are a group of vascular plants that belong to the family Equisetaceae. They are characterized by their jointed stems and are one of the oldest surviving genera of plants.

2. **Characteristics of Equisetum**:
- **Sporophytic Plant Body**: The plant body of Equisetum is sporophytic, meaning it is the diploid phase of the plant life cycle that produces spores.
- **Perennial Herb**: Equisetum is a perennial herb, which means it lives for more than two years and can regrow each season.
- **Size Variation**: The size of Equisetum can vary significantly, ranging from a few centimeters to several meters in height. Some species can grow up to 13 meters tall, while most are less than a meter.
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