Stimulus of vernalisation is perceived by

Options

A. Mature stem apex
B. Embryo of the seed
C. Leaves
D. Both (1) and (2)

Answer

To answer the question "Stimulus of vernalisation is perceived by," we need to analyze the options provided and understand the process of vernalization.

### Step-by-Step Solution:

1. **Understanding Vernalization**: Vernalization is the process by which certain plants require a period of cold temperatures to induce flowering. This is crucial for plants that need to ensure that they flower at the right time of year, typically in spring.

2. **Identifying the Perception of Cold**: The perception of the cold stimulus is essential for the vernalization process. This perception is typically done by specific parts of the plant.

3. **Evaluating the Options**:
- **Mature Stem Apex**: The mature stem apex is involved in growth and development, and it does have meristematic tissues that can respond to environmental stimuli. However, it is not the primary site for perceiving the vernalization stimulus.

- **Embryo of the Seed**: The embryo of the seed can perceive cold temperatures and is crucial for the vernalization process. When seeds are exposed to cold, they can break dormancy and prepare for germination and subsequent flowering.

- **Leaves**: While leaves are important for photosynthesis, they do not play a significant role in the perception of cold for vernalization. Their function is more related to the plant's overall growth rather than the specific stimulus of vernalization.

4. **Conclusion**: Based on the analysis, the correct answers are the mature stem apex and the embryo of the seed. Therefore, the best option is "both 1 and 2."

### Final Answer:
The stimulus of vernalization is perceived by **both the mature stem apex and the embryo of the seed**.