Which of the following plants are water pollinated ?

Options

A. Zostera
B. Vallisneria
C. Hydrilla
D. All of above

Answer

To determine which of the following plants are water pollinated, we need to analyze each option provided: Joistra, Valisneria, and Hydrilla.

### Step-by-Step Solution:

1. **Understanding Pollination**:
- Pollination is the process of transferring pollen grains from the male anthers to the female stigma of flowers. It can occur through various agents, including water, wind, and animals.

2. **Types of Pollination**:
- Water pollination is relatively rare among flowering plants and is primarily found in certain genera, especially among monocotyledons.

3. **Identifying Water Pollinated Plants**:
- **Valisneria**: This is a freshwater plant that is known for its water pollination. The male gametes are released into the water, where they swim to the female flowers.
- **Hydrilla**: Another freshwater aquatic plant that also relies on water for the transfer of its male gametes, making it a water-pollinated species.
- **Joistra**: This refers to marine seagrasses, which are also known to be water pollinated. They thrive in marine environments and utilize water for the transfer of pollen.

4. **Conclusion**:
- All three plants mentioned (Joistra, Valisneria, and Hydrilla) are examples of water-pollinated plants. Therefore, the correct answer is "all of the above."

### Final Answer:
- The correct option is **4th one: all of the above**.