Differentiate between protoxylem and metaxylem.

Explanation

### Step-by-Step Solution:

1. **Definition**:
- **Protoxylem**: This is the first formed part of the xylem in vascular plants. It develops early during the growth of the plant.
- **Metaxylem**: This is the part of the xylem that is formed after protoxylem and develops later in the plant's growth.

2. **Position**:
- **Protoxylem**: It is located closer to the periphery of the root or stem.
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