The stimulus of cold treatment (vernalisation) is perceived by

Options

A. leaves
B. flowers
C. roots
D. shoot apices

Answer

To solve the question regarding the stimulus of cold treatment (vernalisation) and where it is perceived, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Vernalization**:
- Vernalization is the process where plants are exposed to a period of cold temperatures to induce flowering. This is crucial for many plants that require a cold period to transition from the vegetative stage to the flowering stage.

**Hint**: Remember that vernalization is specifically related to cold treatment and its effect on flowering.

2. **Identify the Perception of Cold Stimulus**:
- The cold stimulus is perceived by actively dividing cells in the plant. These cells are primarily located in the shoot apices, which are the growing tips of the plant.

**Hint**: Focus on the parts of the plant that are involved in growth and development, particularly those that are actively dividing.

3. **Role of Shoot Apices**:
- The shoot apices are responsible for receiving the cold stimulus and then transmitting this information throughout the plant. This is where the hypothetical hormone, known as vernalin, is thought to be produced.

**Hint**: Consider the significance of the shoot apices in plant growth and how they relate to flowering.

4. **Conclusion**:
- Based on the understanding that the shoot apices are the parts of the plant that perceive the cold treatment, we can conclude that the correct answer to the question is the shoot apices.

**Hint**: Always relate back to the main question to ensure that your conclusion directly answers it.

### Final Answer:
The stimulus of cold treatment (vernalisation) is perceived by the **shoot apices**.