Which of the following statements is not correct?

Options

A. Pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil.
B. Some reptiles have also been reported as pollinators in some plant species
C. Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style.
D. Insects that consume pollen or nectar without bringing about pollination are called pollen / nectar robbers.

Answer

To determine which statement is not correct, let's analyze each statement one by one:

1. **Statement 1**: "The pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil."
- This statement is correct. The interaction between the chemical components of pollen and the pistil is essential for pollen germination and the growth of the pollen tube.

2. **Statement 2**: "Some reptiles have also been reported as pollinators in some plant species."
- This statement is also correct. Certain reptiles, such as some species of lizards, have been observed to act as pollinators for specific plants.

3. **Statement 3**: "The pollen grains of many species can germinate on the stigma of a plant, but only one pollen tube of the same species grows into this type."
- This statement is incorrect. While pollen grains from many species can land on a stigma, they cannot germinate unless they are from the same species as the flower. Only pollen grains from the same species can germinate and grow a pollen tube into the ovary.

4. **Statement 4**: "The insects that consume pollen or nectar without bringing about pollination are called pollen or nectar robbers."
- This statement is correct. Insects that take nectar or pollen without aiding in the pollination process are indeed referred to as robbers.

Based on this analysis, the incorrect statement is **Statement 3**.

### Summary of the Solution:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect (pollen grains must be from the same species to germinate)
- Statement 4: Correct

### Conclusion:
The statement that is not correct is **Statement 3**.

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