Cabomba caroliniana (Naturalized)

Green Cabomba, Fanwort, Carolina Fanwort, Fish grass, Washington grass

Cabomba caroliniana
, commonly known as Green Cabomba, is an aquatic perennial herbaceous plant native to North America 
Fanwort is a submersed, sometimes floating, but often rooted, freshwater perennial plant with short, fragile rhizomes. The erect shoots are upturned extensions of the horizontal rhizomes. The shoots are grass green to olive green or sometimes reddish brown. The leaves are of two types: submersed and floating. The submersed leaves are finely divided and arranged in pairs on the stem. The floating leaves, when present, are linear and inconspicuous, with an alternate arrangement. They are less than 1/2 inch (13 mm) long and narrow (less than 1/4 inch or 6 mm). The leaf blade attaches to the centre, where there is a slight constriction. The flowers are white and small (less than 1/2 inch (13 mm) in diameter), and are on stalks which arise from the tips of the stems.
Grows rooted in the mud of stagnant to slow flowing water, including streams, smaller rivers, lakes, ponds, sloughs, and ditches. In some States in the United States it is now regarded as a weed. Fanwort stems become brittle in late summer, which causes the plant to break apart, facilitating its distribution and invasion of new waterbodies. It produces by seed but vegetative reproduction seems to be its main vehicle for spreading to new waters.
Large numbers of plants are sent from Florida to the rest of the U.S. for commercial use. Fanwort is also grown commercially in Asia for export to Europe and other parts of the world. Small-scale, local cultivation occurs in some area and aquarists are probably responsible for some introductions.
A nutriment rich water on the soft side. Additional carbon dioxide will encourage strong growth. The easiest of the Cabomba species to grow in the aquarium but needs a strong bright light. Plant in groups. Can grow fast in good conditions. If the water circulation is too strong or with some fish (which like to nibble at it), because of its brittle stems, filters may become clogged. 
(From Wikipedia on 24.1.14)

The aquatic plant Cabomba caroliniana in flower is seen in these pictures taken from a small dammed river in Kozhikode, Kerala.
The underwater leaves are highly dissected and fan like whereas the surface leaves of the flowering stems are entire and triangular in shape. The flowers are pink in colour.
You can see the carpet of flowers in the long shot of the habitat. I hope the id is correct. I am not aware of the status of its distribution in India and whether it is an exotic escaped from ornamental aquaria plants.
Thanks ... for this beautiful and interesting post. Cabomba caroliniana is reported to be a native of the Americas, and naturalized elsewhere.
I think the pink flowered form is uncommon, and it is not widely represented in www.
FNA states that "...In parts of the southeastern United States, plants with purple-tinted flowers, possibly a response to some environmental factor, have been treated as Cabomba caroliniana var. pulcherrima..."
Thank you very much ... for the information.