Balloon-like swellings formed by xylem parenchyma inside the xylem vessels through pits are

Options

A. (a) Tracheal plug
B. (b) Tyloses
C. (c) Callose
D. (d) Both (a) and (b)

Answer

To answer the question regarding the balloon-like swellings formed by xylem parenchyma inside the xylem vessels through pits, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Xylem Structure**:
- Xylem is a type of vascular tissue in plants responsible for the transport of water and nutrients. It consists of various cell types, including xylem vessels and xylem parenchyma.

2. **Identifying the Phenomenon**:
- The question refers to balloon-like swellings that occur within xylem vessels. This phenomenon is known as "pylosis" or "tracheal plug."

3. **Role of Xylem Parenchyma**:
- Xylem parenchyma cells can swell and form these structures through pits, which are small openings that connect the xylem vessels to the parenchyma.

4. **Function of Pylosis**:
- These swellings serve an important function by providing protection against decay and preventing the spread of disease within the plant.

5. **Correct Terminology**:
- The swellings can be referred to as "tracheal plugs" because they effectively block the flow within the xylem vessels, acting as a plug.

6. **Evaluating Options**:
- Given the options:
- A) Tracheal plug
- B) Pylosis
- C) Callus
- D) Both A and B
- Options A and B are both correct as they refer to the same phenomenon.

7. **Final Answer**:
- Therefore, the correct answer is option D) Both A and B.