....... are plants without vascular system and the body is not differentiated into root, stem and leaves.

Explanation

**Step-by-Step Solution:**

1. **Identify the Characteristics of the Plants in Question:**
- The question asks for plants that lack a vascular system.
- Additionally, their body structure is not differentiated into roots, stems, and leaves.

2. **Define Vascular System:**
- A vascular system in plants consists of specialized tissues (xylem and phloem) that transport water, nutrients, and food throughout the plant.
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