Which is a character of Castor plant to avoid autogamy?
(a) Unisexuality
(b) Porogamy
(c) Protandry
(d) Heterostyly

Options

A. Unisexuality
B. Porogamy
C. Protandry
D. Heterostyly.

Answer

To solve the question, "Which is a character of Castor plant to avoid autogamy?", we need to analyze the options provided and understand how they relate to the reproductive characteristics of the Castor plant.

### Step-by-Step Solution:

1. **Understanding Autogamy**:
- Autogamy refers to self-pollination, where pollen from the same flower fertilizes its ovules. To avoid autogamy, a plant must have mechanisms that promote cross-pollination.

2. **Analyzing the Options**:
- **(a) Unisexuality**: The Castor plant has unisexual flowers, meaning that it has separate male and female flowers. This characteristic prevents self-pollination because a single flower cannot fertilize itself. Instead, pollen must be transferred from male flowers to female flowers, promoting cross-pollination.
- **(b) Porogamy**: This term refers to the entry of a pollen tube through the micropyle of the ovule. It does not relate to the avoidance of autogamy.
- **(c) Protandry**: This is a condition where an organism starts as male and later becomes female. While this can help in some plants to avoid self-fertilization, it does not specifically apply to the Castor plant.
- **(d) Heterostyly**: This refers to the presence of styles of different lengths in the same species. While it can facilitate cross-pollination, it is not a defining characteristic of the Castor plant.

3. **Conclusion**:
- The Castor plant's primary mechanism to avoid autogamy is its unisexuality. Therefore, the correct answer is **(a) Unisexuality**.

### Final Answer:
(a) Unisexuality

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