Nontransfer of pollen from anther to stigma of the same flower due to a mechanical barrier is

Options

A. Dichogamy
B. Herkogamy
C. Heterostyly
D. Cleistogamy.

Answer

To solve the question regarding the non-transfer of pollen from the anther to the stigma of the same flower due to a mechanical barrier, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the term that describes the situation where pollen cannot transfer from the anther to the stigma of the same flower because of a mechanical barrier.

2. **Identifying Key Terms**: The terms related to pollination include self-pollination, cross-pollination, and various mechanisms that plants have evolved to prevent self-pollination.

3. **Evaluating the Options**:
- **Dichogamy**: This refers to the maturation of male and female reproductive parts at different times. It does not directly address mechanical barriers.
- **Hercogamy**: This specifically refers to a mechanical barrier that prevents self-pollination by ensuring that the anthers and stigma are positioned in such a way that pollen cannot transfer from one to the other.
- **Heterostyle**: This involves flowers having different lengths of styles and stamens, which can facilitate cross-pollination but does not directly relate to mechanical barriers.
- **Clistogamy**: This refers to flowers that do not open and thus only self-pollinate, which is not relevant to the question.

4. **Choosing the Correct Answer**: Based on the definitions, **Hercogamy** is the correct term that describes the mechanical barrier preventing the transfer of pollen from the anther to the stigma of the same flower.

5. **Conclusion**: The answer to the question is **Hercogamy**.