Weed in the Windrush

As I took the back route into town today I was struck by how attractive this weed looked on the bed of the River Windrush and with the clear water flowing over it.

Apologies for my reduced presence the last couple of days as we have been decorating the kitchen. Another coat of paint is needed but so far s good.

If any of you are keen gardeners I would really appreciate you looking at my backblip from yesterday and letting me know the name of the plant if you recognise it. Many Thanks.