In Vallisneria

Options

A. The female flower reaches the surface of water by the long stalk
B. The female flowers are released on to the surface of water
C. Female flowers remain submerged in water
D. Pollen grains are released inside the water

Answer

### Step-by-Step Solution:

1. **Understanding Vallisneria**: Vallisneria is a genus of freshwater aquatic plants commonly known as eelgrass or tapegrass. It is a submerged plant that can form extensive underwater meadows.

2. **Dioecious Nature**: Vallisneria is dioecious, meaning that individual plants produce either male or female flowers. This is important for understanding how reproduction occurs in this plant.

3. **Female Flower Structure**: The female flowers of Vallisneria are borne on long stalks that extend up to the surface of the water. This adaptation allows them to be positioned at the water's surface for effective pollination.

4. **Male Flower Characteristics**: Male flowers are much smaller than female flowers and are produced in large numbers. They mature underwater and eventually detach from the inflorescence.

5. **Pollination Process**: Once the male flowers float to the surface, they rely on water currents to disperse their pollen. The tiny male flowers act like rafts filled with pollen, which then come into contact with the female flowers at the surface, leading to pollination.

6. **Evaluating the Options**:
- **Option 1**: "The female flower reaches the surface of water by the long stalk." - This statement is true.
- **Option 2**: "The female flowers are released onto the surface of water." - This statement is false; it applies to male flowers.
- **Option 3**: "Female flowers remain submerged in water." - This statement is false; female flowers are at the surface.
- **Option 4**: "Pollen grains are released inside the water." - This statement is also false; pollen grains are released at the surface.

7. **Conclusion**: The correct answer is the first option: "The female flower reaches the surface of water by the long stalk."