Why are xylem and phloem called complex tissues?

Explanation

### Step-by-Step Solution

1. **Understanding Tissue Types**:
- Tissues in plants are classified into two main categories: simple tissues and complex tissues.
- Simple tissues consist of only one type of cell, while complex tissues are made up of more than one type of cell.

2. **Definition of Complex Tissues**:
- Complex tissues are those that contain different types of cells that work together as a functional unit.
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