The baloon like outgrowth of parenchyma in the lumen of a vessel is known as

Options

A. histogen
B. tyloses
C. phellogen
D. tunica

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe a balloon-like outgrowth of parenchyma in the lumen of a vessel.

2. **Identifying the Correct Term**: The term that describes this structure is "tylosis." Tylosis is specifically an outgrowth of parenchyma cells that occurs in the xylem vessels.

3. **Function of Tylosis**: Tylosis serves an important function in plants. When a plant experiences stress, such as drought or infection, tylosis can form to block the xylem vessels. This helps to prevent further damage to the plant by stopping the spread of pathogens or reducing water loss.

4. **Differentiating from Other Terms**: The question provides other options such as histogens, fallogen, and tunica.
- **Histogens** refer to regions of primary tissues.
- **Fallogen** is a layer of meristematic cells responsible for the development of periderm.
- **Tunica** refers to the outer layer of cells in the growing plant apex.

5. **Conclusion**: After analyzing the definitions and functions of the terms, it is clear that the correct answer to the question is "tylosis."

**Final Answer**: The balloon-like outgrowth of parenchyma in the lumen of a vessel is known as **tylosis**.

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