It does send out these shoots across the pond when it is ready to get into flower motion. It sends out lots of long runners horizontally and then up out of those come the vertical shoots which then have the flowers. I love it when it does this as I can see how much of it will be flowering. Obviously with a small pond no one wants it to cover all their water surface. It is just like the watercress really the speed it grows. So you have to keep this is mind when you put it in. I have just been and pulled out some more of the watercress as the rain that we have had over the last two days has really flattened it so that it won't recover completely.
Damp you are so lucky to have the newts, our watercress isn't so obliging.