Potamogeton species?- Thattekad, Kerala

 
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Wild Flower for Bot. ID-261209-RK-3 : Attachments (1). 7 posts by 3 authors.
Growing on river surface. I think these plants are used in aquariums. Pic taken at 4.45 pm on 09-12-09. Periyar River, Thattekad, Kerala.
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Looks like Myriophyllum spicatum.

I think there are more than one species. But that doesn’t look like M. spicatum to me. Leaves are dissected from the base and not from the midrib. The submerged plant with dissected leaf seems to be like that of Cabomba sp. may be aquatica.
Another plant seems to be Potamageton (the one with flowers and leaves on the water surface!!).
Potamegeton is not usually used in aquariums, I tired, but my fishes died :((.
May be you are right, it is not Myriophyllum. If it is Cabomba then we should be seeing some entire floating leaves; what about Ceratophyllum?.
In both latter cases, the spikes should belong to Potamogeton, of which narrow leaves are seen vaguely in the background.