Marginal Plants

your advice please.....

i have my own fishing lake, 100 odd yards long, 30 yards wide, along the
length it starts shallow and progresses to about 5 feet, and 3 feet, 5 ft
one end, 3 ft the other, what i need is some sort of floating marginal/edge
cover that is different, i saw some floating/growing plants at Stafford Moor
Fishery, but i forgot to ask what the plant was,
It resembles a mass of floating branches with shoots growing out of them..

Your help would be much appreciated...

And any ideas for marginal plants besides lillies, iris, rushes and reeds,
would be nice to make it look that little bit different..

sean