Wasserbestäubung

Wasserbestäubung, also known as hydrophily, is a pollination mechanism where pollen is transferred by water. This mode of pollination is relatively rare, occurring in about 2% of all angiosperms. It is most commonly found in aquatic plants, where the entire life cycle of the plant is dependent on water.

There are two main types of water pollination:

1. Epihydrophily: In this type, pollen floats on the surface of the water and is carried by currents to other flowers. This is observed in plants like Vallisneria. The pollen grains are typically light, hydrophobic, and possess air spaces that aid flotation.

2. Hypohydrophily: Here, pollen is released underwater and transported by water currents. This is seen in plants like Zostera (seagrasses). The pollen grains are often long, ribbon-like, and lack a resistant outer wall (exine), making them adapted to an underwater environment.

Plants that rely on water pollination often have specific adaptations. Their flowers may lack the bright colors and strong scents that attract insects or birds, as these are irrelevant in an aquatic setting. Instead, they often produce large quantities of lightweight pollen to increase the chances of successful pollination. The stigmas of these plants are frequently feathery or branched to effectively catch the passively drifting pollen. While rare, water pollination is a highly effective strategy for certain aquatic and semi-aquatic plant species, enabling them to reproduce in their specialized environments.