The pressure of a. Physical berries between stigma and stamen prevents autogamy. This phenomenon is called as

Options

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

Answer

To solve the question regarding the phenomenon that prevents autogamy due to a physical barrier between the stigma and stamen, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- Autogamy refers to self-fertilization, where pollen from the same flower fertilizes its ovules.
- Stigma is the part of the flower that receives pollen, while the stamen is the male reproductive part that produces pollen.

2. **Identify the Physical Barrier**:
- The question mentions a physical barrier between the stigma and stamen. This barrier can prevent the pollen from the stamen of the same flower from reaching its stigma.

3. **Recognize the Phenomenon**:
- The phenomenon that describes this situation is known as "hercogamy." Hercogamy is a mechanism that promotes cross-pollination by ensuring that the stigma and stamen do not function simultaneously, thus preventing self-fertilization.

4. **Consider Other Options**:
- Heterostylia refers to flowers having stamens of different lengths, which does not directly relate to the physical barrier preventing autogamy.
- Dichogamy is the maturation of stamen and stigma at different times, which also helps avoid self-pollination but is not specifically about a physical barrier.
- Clistogamy refers to closed flowers that do not open and typically self-pollinate, which is the opposite of what the question describes.

5. **Conclusion**:
- Based on the definitions and explanations, the correct answer to the question is "hercogamy."

### Final Answer:
The phenomenon that prevents autogamy due to a physical barrier between stigma and stamen is called **hercogamy**.

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