It appeals to me more than the more usual persicarias - wonder where it came from? Did you sniff the flowers?

Whatever it is it's very pretty Landgirl. The birds are good at dropping different seeds in my garden or maybe this just got blown in by the wind.

I have it growing as Percicaria capitata - a highly invasive and spreading weed. I yank it out all the time. It may not do that for you, but it grows any and every where here.

I believe that it may not be completely hardy in the UK, so hopefully it won't be invasive here!