In a twiner, the twining structure is

Options

A. Tendril
B. Spine/thorn
C. Curved hook
D. Sensitive stem

Answer

To solve the question "In a twiner, the twining structure is," we will analyze the options provided and determine which one correctly describes the twining structure of a twiner.

### Step-by-Step Solution:

1. **Understand the Definition of Twinners**:
- Twinners are climbing plants that have weak stems. They require external support to climb, such as ropes or rods.

2. **Identify the Characteristics of Twinners**:
- Twinners have a sensitive stem that can detect touch. This sensitivity allows them to coil around supports as they grow.

3. **Analyze the Options**:
- **Tendril**: This is a modified stem that is thread-like and helps in climbing.
- **Spine or Thorn**: These are pointed structures that are also modified stems, but they do not serve the purpose of twining.
- **Curved Hook**: These structures assist in climbing but are not the primary twining mechanism in twinners.
- **Sensitive Stem**: This is the correct option as it refers to the twining structure that allows the plant to sense and wrap around supports.

4. **Conclusion**:
- Based on the analysis, the twining structure in a twiner is a **sensitive stem**.

### Final Answer:
The twining structure in a twiner is a **sensitive stem**.

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