Which of these is not a contrivance for cross pollination ?

Options

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

Answer

To determine which of the given options is not a contrivance for cross-pollination, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Cross-Pollination**: Cross-pollination occurs when pollen from one flower fertilizes the ovule of another flower. This process increases genetic diversity in plants.

2. **Analyzing Option A: Diclini**:
- Diclini refers to a monoecious condition where plants have separate male (staminate) and female (pistillate) flowers on the same plant.
- This condition can facilitate cross-pollination since the male and female flowers are on the same plant, but they are separate, allowing for pollen transfer from one flower to another.

3. **Analyzing Option B: Dicogamy**:
- Dicogamy is the phenomenon where the male and female gametes mature at different times.
- This timing difference prevents self-fertilization and promotes cross-pollination, as it encourages pollen from other plants to fertilize the ovules.

4. **Analyzing Option C: Clistogamy**:
- Clistogamy refers to flowers that are closed and typically self-fertilizing.
- Since the flowers do not open, the pollen cannot be transferred to other flowers, making cross-pollination impossible. Therefore, this option does not support cross-pollination.

5. **Analyzing Option D: Hercogamy**:
- Hercogamy is characterized by a spatial separation of the stamens and pistils, which prevents self-pollination.
- This arrangement encourages cross-pollination as pollen from other flowers must be transferred to the stigma.

6. **Conclusion**:
- After analyzing all the options, it is clear that **Clistogamy (Option C)** is not a contrivance for cross-pollination, as it involves self-fertilization in closed flowers.

### Final Answer:
**C. Clistogamy**

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