The photoperiod in plants is perceived at

Options

A. meristem
B. flower
C. floral buds
D. leaves

Explanation

To answer the question "The photoperiod in plants is perceived at," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photoperiod**:
- Photoperiod refers to the length of time a plant is exposed to light in a 24-hour cycle. It is crucial for regulating flowering and other developmental processes in plants.

2. **Identifying the Perception Site**:
- The question asks where the photoperiod is perceived in plants. The options given are meristem, flower, floral buds, and leaves.

3. **Reviewing Experimental Evidence**:
- It has been experimentally demonstrated that the photoperiodic stimulus is perceived by the leaves of the plant. This is based on various observations.

4. **Observations Supporting Leaf Perception**:
- **Observation 1**: A plant from which all leaves have been removed fails to flower, even when it receives the necessary inductive light cycles. This indicates that leaves are essential for perceiving photoperiod.
- **Observation 2**: In the plant Xanthium, which is a short-day plant, flowering occurred when just one-eighth of a leaf was exposed to short days. This further supports the idea that leaves are the primary site for photoperiod perception.

5. **Conclusion**:
- Based on the experimental evidence and observations, we conclude that the photoperiod in plants is perceived at the leaves.

### Final Answer:
The photoperiod in plants is perceived at **leaves** (Option 4).

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