Tendrils and twiners come in contact with their support by means of

Options

A. Nutation
B. Thigmonasty
C. Thigmotropism
D. Anemotropism.

Answer

To answer the question "Tendrils and twiners come in contact with their support by means of," we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Tendrils and Twiners**:
- Tendrils are specialized plant structures that help plants climb and support themselves by wrapping around objects. Twiners are plants that twine around supports as they grow.

**Hint**: Consider what mechanisms plants use to interact with their environment for support.

2. **Evaluating the First Option - Nodding**:
- Nodding refers to the bending of plant parts due to unequal growth rates. This is not the mechanism by which tendrils and twiners contact their supports.

**Hint**: Think about whether bending alone can help a plant attach to a support.

3. **Evaluating the Second Option - Thigmonasty**:
- Thigmonasty is a type of movement in plants in response to touch, such as the rapid movement of the tentacles of the Drosera plant when they come into contact with insects. However, this is not the primary mechanism for tendrils and twiners to attach to supports.

**Hint**: Consider whether this type of movement is more about rapid response or a sustained attachment.

4. **Evaluating the Third Option - Thigmotropism**:
- Thigmotropism is the directional growth of a plant in response to touch or physical contact with a solid object. Tendrils and twiners exhibit thigmotropism as they grow and wrap around their supports.

**Hint**: Focus on the term that describes growth in response to touch, rather than just movement.

5. **Evaluating the Fourth Option - Anemotropism**:
- Anemotropism refers to the movement of plant parts in response to air currents. This is not relevant to how tendrils and twiners attach to their supports.

**Hint**: Think about whether wind or air movement plays a role in how tendrils attach to something solid.

### Conclusion:
The correct answer is **Thigmotropism**. Tendrils and twiners come into contact with their support through thigmotropism, which is the growth response to touch.