Tyloses thickenings are seen in

Options

A. collenchyma
B. phloem cells
C. ray parenchyma only
D. ray parenchyma and xylem cells

Answer

### Step-by-Step Solution:

1. **Understanding Tylosis**: Tylosis refers to the formation of balloon-like structures that develop in certain plant cells. These structures are typically associated with the xylem tissue.

2. **Identifying Cell Types**: The question lists four options regarding where tylosis thickenings can be found:
- A) Collenchyma
- B) Phloem cells
- C) Ray parenchyma only
- D) Ray parenchyma in the xylem cells

3. **Analyzing Each Option**:
- **Option A (Collenchyma)**: Tylosis is not found in collenchyma cells. Collenchyma provides support and is not involved in water transport.
- **Option B (Phloem cells)**: Tylosis is also absent in phloem cells, which are responsible for transporting nutrients rather than water.
- **Option C (Ray parenchyma only)**: While tylosis can occur in ray parenchyma, it is not limited to just this cell type.
- **Option D (Ray parenchyma in the xylem cells)**: This option correctly identifies that tylosis can be found in both ray parenchyma and xylem cells, particularly in the heartwood.

4. **Conclusion**: The correct answer is Option D, as tylosis thickenings are indeed seen in ray parenchyma within xylem cells.

### Final Answer:
Tyloses thickenings are seen in **ray parenchyma in the xylem cells**.

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