Bryophytes seldom reach a height of more than 20 cm because they

Options

A. Lack vascular system
B. Lack roots
C. Lack mechanical tissues
D. All the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Bryophytes:**
- Bryophytes are a group of non-vascular plants that include mosses, liverworts, and hornworts. They are characterized by their simple structure and lack of specialized vascular tissues.

2. **Vascular System Absence:**
- One of the main reasons bryophytes do not grow taller than 20 cm is their lack of a vascular system. Vascular plants have specialized tissues (xylem and phloem) that transport water, nutrients, and food throughout the plant. In contrast, bryophytes rely on diffusion for the movement of substances, which limits their size.

3. **Lack of Roots:**
- Bryophytes do not have true roots; instead, they have structures called rhizoids that anchor them to the substrate. These rhizoids are not effective in absorbing water and nutrients like true roots, which further restricts their growth potential.

4. **Absence of Mechanical Support:**
- Bryophytes lack proper mechanical tissues that provide structural support. This absence means they cannot support a tall structure, making it difficult for them to grow beyond a certain height.

5. **Moist Habitat Preference:**
- Bryophytes thrive in moist environments, which is essential for their reproduction and nutrient absorption. Their dependence on moisture also limits their ability to grow taller, as they need to maintain hydration.

6. **Conclusion:**
- Therefore, the reason bryophytes seldom reach a height of more than 20 cm is due to their non-vascular nature, lack of true roots, absence of mechanical tissues, and preference for moist habitats.

**Final Answer:**
Bryophytes seldom reach a height of more than 20 cm because they are non-vascular, lack true roots, and do not have proper mechanical tissues for support.

---