Write a note on the characteristics of plants pollinated by water.

(N/A) Pollination by water is quite rare in flowering plants,as most aquatic plants rely on insects or wind for pollination.
Key characteristics and mechanisms include:
$1$. Rare occurrence: Water pollination is limited to about $30$ genera,mostly monocotyledons.
$2$. Examples: Includes freshwater plants like $Vallisneria$ and $Hydrilla$,and marine seagrasses like $Zostera$.
$3$. Surface pollination: In $Vallisneria$,the female flower reaches the water surface via a long,coiled stalk. Male flowers or pollen grains are released onto the water surface and carried passively by water currents to reach the female flower's stigma.
$4$. Submerged pollination: In seagrasses,flowers remain submerged. Pollen grains are long and ribbon-like,allowing them to be carried passively within the water to reach the stigma.
$5$. Protection: In most water-pollinated species,pollen grains are protected from wetting by a mucilaginous covering.
$6$. Floral traits: Flowers pollinated by water (like those pollinated by wind) are generally not very colourful and do not produce nectar.