Tyloses are

Options

A. Wound-healing secretions
B. Responsible for plugging the lumen of vessels
C. Special epidermal hairs covering stomata in xerophytes
D. Callus secertion on sieve plates

Answer

### Step-by-Step Solution:

1. **Definition of Tyloses**: Tyloses are balloon-like outgrowths that originate from the xylem parenchyma cells in the xylem vessels of angiospermic plants.

2. **Location**: These structures are found in the xylem vessels, which are responsible for the conduction of water and minerals in plants.

3. **Formation**: Tyloses form when the xylem parenchyma adjacent to the xylem vessels expands and protrudes into the lumen of the vessel, creating a balloon-like structure.

4. **Function**: The primary function of tyloses is to plug the lumen of the xylem vessels. This plugging action hinders the flow of water and minerals, which can help prevent the spread of infections caused by pathogens (like bacteria) that may be present in the soil.

5. **Conclusion**: Therefore, tyloses play a crucial role in the plant's defense mechanism by preventing the entry of pathogens through the xylem vessels.

6. **Correct Option**: Based on the explanation, the correct answer to the question "Tyloses are" is that they are responsible for plugging the lumen of the vessel.