Think this is Thread-leaved Water Crowfoot, at Gartmorn Dam recently. Daisy-like flowers, and it likes slow-moving waters. It has rounded seedheads which become covered with bristles. A bit more about it here:
https://www.naturespot.org.uk/species/thread-leaved-water-crowfoot

#ScottishWildlife #ScottishWildflowers #AquaticFlowers