Now those are cool and had to go look them up and found this:
Stratiotes aloides
From Wikipedia, the free encyclopedia
Stratiotes aloides
Stratiotes aloides
Statiotes aloides, commonly known as the
water soldier or
water pineapple, is a submerged
aquatic plant native to
Europe and northwestern
Asia. In Britain it was once common in East Anglia and still is in many places, particularly wet ditches and healthy ponds.
Description
S. aloides has a
rosette of serrated
leaves. White
flowers are produced in the summer.
Ecological aspects
In the summer this plant floats on the water surface with the
leaves just above the surface. In the Autumn they become covered with a slimy secretion (calcium carbonate) and the whole plant sinks to the bottom to rise again in the Spring. Fossils have been found of this plant.
Plants are dioecious, male and female plants must be grown if seed is required. Only the female plant occurs naturally in Britain, though plants with hermaphrodite flowers are also found occasionally. Seed is never set in Britain, the plants increasing mainly by offsets.
Cultivation
Most suitable for the cool
aquarium or
pond.
Propagation from runners which form from the centre of the
rosette of
leaves.
The herb has had a high reputation for treating wounds, especially when these are made by an iron implement. It is applied externally. The plant is also said to be of use in the treatment of St. Anthony's Fire and also of bruised kidneys.