When pollen grains are not transferred from rahthers to stigma in a flower, due to the physical barrier, it is called

Options

A. cleistogamy
B. herkogamy
C. dichogamy
D. heterogamy

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about a situation where pollen grains are not transferred from the anthers to the stigma of a flower due to a physical barrier. This process is related to pollination.

2. **Identifying the Options**: The options provided are:
- A) Cleistogamy
- B) Herkogamy
- C) Dykogamy
- D) Heterogamy

3. **Defining Each Term**:
- **Cleistogamy**: This refers to a type of self-pollination that occurs in closed flowers where pollen is not exposed to the external environment.
- **Herkogamy**: This is a mechanism that prevents self-pollination by spatially separating the male (anthers) and female (stigma) reproductive parts within the flower.
- **Dykogamy**: This involves the maturation of stamens and pistils at different times to prevent self-fertilization.
- **Heterogamy**: This term generally refers to differences in reproductive structures or processes but is not specifically related to the physical barrier preventing pollen transfer.

4. **Analyzing the Correct Answer**: Since the question specifically mentions a physical barrier preventing the transfer of pollen from the anthers to the stigma, the correct answer is **B) Herkogamy**. This is because herkogamy involves a spatial separation that serves as a physical barrier between the male and female parts of the flower.

5. **Conclusion**: Therefore, when pollen grains are not transferred from anthers to stigma due to a physical barrier, it is called **Herkogamy**.

---