Chalazogamy occurs in

Options

A. Cucurbita
B. Lily
C. Populus
D. Casuarina.

Answer

To determine where chalazogamy occurs, we need to understand the term and the options provided:

1. **Definition of Chalazogamy**: Chalazogamy is a type of fertilization process in plants where the pollen tube enters the ovule through the chalazal end. This is one of the ways pollen can reach the ovule for fertilization.

2. **Analyzing the Options**:
- **Cucurbita**: This plant exhibits mesogamy, where the pollen tube enters through the integument.
- **Lily**: The lily plant shows porogamy, where the pollen tube enters through the micropyle.
- **Populus**: Similar to Cucurbita, Populus also shows mesogamy.
- **Casuarina**: This plant is known to exhibit chalazogamy, where the pollen tube enters through the chalazal end.

3. **Conclusion**: Based on the definitions and characteristics of each plant, the correct answer to the question "Chalazogamy occurs in" is **Casuarina**.

### Final Answer:
Chalazogamy occurs in **Casuarina**.