Can't ID all of them, but here's what I've got:
#1 is a Ludwigia of some kind
#2 & #11 are, as others have indicated, a watercress species, perhaps N. officianale (formerly Rorippa nasturtium-aquaticum). If that's indeed what it is, it's also edible (not that I'm recommending you eat it).
#5 reminds me of some of the African Ammannia species I've seen. If I had to guess I'd pick something from that genus, maybe A. senegalensis?
#6 looks like Stuckenia pectinata, or at least something similar
#7 another Ludwigia species
#9 looks like a Ranunculus species, maybe R. repens?
#12 a Hydrocotyle species.
Flowers from any of the plants would help us ID them