The pressure of a physical barrier 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 1: Understand the Terms
- **Autogamy**: This is a form of self-fertilization where a flower fertilizes itself.
- **Stigma**: The part of the flower that receives pollen.
- **Stamen**: The male reproductive part of a flower, which produces pollen.

### Step 2: Analyze the Options
1. **Hercogamy**: This term refers to the spatial separation between the anthers (male) and the stigma (female) in hermaphroditic flowers, which prevents self-fertilization.
2. **Heterostyle**: This refers to flowers having styles of different lengths to reduce self-fertilization but does not involve a physical barrier.
3. **Chasmogamy**: This is the condition where flowers open and allow for cross-fertilization, which does not involve a physical barrier.
4. **Clestogamy**: This refers to self-fertilization occurring in closed flowers, which is the opposite of preventing autogamy.

### Step 3: Identify the Correct Answer
- The option that describes a physical barrier preventing autogamy is **Hercogamy**. This phenomenon involves the spatial separation of the anthers and stigma, effectively preventing self-fertilization.

### Final Answer
The pressure of a physical barrier between stigma and stamen prevents autogamy. This phenomenon is called **Hercogamy**.

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