In Cycas the microsporangia are born on which side of microsporophyll :–

Options

A. Adaxial
B. Abaxial
C. Lateral
D. Terminal

Answer

**Step-by-Step Solution:**

1. **Understanding the Structure**: In Cycas, the microsporangia are found on the microsporophyll, which is a leaf-like structure that bears the microsporangia.

2. **Defining Surfaces**: The terms used to describe the surfaces of the microsporophyll are:
- **Adaxial**: The upper surface.
- **Abaxial**: The lower surface.
- **Lateral**: The sides.
- **Terminal**: The end.

3. **Identifying the Location**: The microsporangia in Cycas are specifically located on the abaxial surface of the microsporophyll.

4. **Counting Microsporangia**: In a single microsporophyll (or Saurus), there can be 3 to 6 microsporangia. The number can vary among different species of Cycas:
- Cycas sarsenalis: Approximately 700 microsporangia.
- Cycas revoluta: Approximately 1000 microsporangia.
- Cycas media: Approximately 1150 microsporangia.

5. **Structure of Microsporangia**: Each microsporangium is characterized as a short-stalked, oval or elliptical structure. The development of these sporangia is of the eusporangiate type.

6. **Wall Layers**: Each microsporangium has 5 to 6 layers of walls. The outermost layer is called the exothecium, while the innermost layer is known as the tapetum, which provides nourishment to the developing spores.

7. **Final Answer**: Based on the above information, the microsporangia in Cycas are born on the abaxial surface of the microsporophyll. Therefore, the correct answer is option 2: Abaxial surface.

---