I took this picture at my workplace yesterday showing
Persicaria polymorpha for comparison. The plant on the right has been undisturbed for two or three years. There were originally three but I had to move the other two for some projected construction work. A little piece got left behind and as a consequence is behind in growth and flowering, see the left one which is shorter with the flowers later and still white. The picture is a bit dull as it was taken around 6.30 a.m. just around dawn.
I also have the picture in higher resolution, and also others closer-up if that would help. I thought I read somewhere that we should keep images below 500k. Not sure if I'm remembering that right, but just to be on the safe side I resized.....