Sorry not much help here, I have a pond, but don't recognise the plants. Are they purchased from a store or wild? The first one kind of looks like cardinal lobelia, but very small. The "watercress" plant reminds me of something from an aquarium store. The last pix looks vaguely like primrose. But no bells going off here for sure. Good Luck
Imp- maybe try the easy garden site. There's an id this plant forum.
These are wild plants collected in Colorado pond at an elevation of 5,500'.
I think that IS a type primrose! Good call!
The leaves are very firm. It could be Primula veris (Cowslip) or Primula Elatior (Oxlip). I will watch to see what color flowers it produces (I walk near the pond I got it from often)
Does the first one get little blue flowers? There is a Forget-me-not that grows in wet areas that looks similar. Looking again... maybe not... but here is a LIST