water plants rely more on vegetative
reproduction than on seeds for dispersal. In vegetative reproduction fragments of
plants, or specialised structures may be carried away by water currents to grow elsewhere.
This kind of reproduction is asexual. Canadian Pond Weed
introduced into Britain has spread entirely this way. All known populations in Europe are
solely female. However, seeds are still important for dispersal in other water plants.
Plants which produce their flowers well above the water level often have seeds that will
float and are dispersed by water. However not all plants which grow above the water have
water dispersed seeds.
Plants such as Pond Iris grow in or near
freshwater. The seed pods break open when they ripen. Those which fall into the water
float away. The seeds may be dispersed long distances in this way. They can either
germinate in the water or when they become stranded on mud.