From what I understand, it is the color and the flowers will change color once they have been pollinated. At least that is what I have been told on a couple of nature hikes. The change in color may only be slight but it lets the pollinators know that they can skip that particular bloom.
@autumnseden Thank you Autumn for your reply ..now that's interesting..I didn't know that..will have to watch them now. I saw that bee going from one to another until it settle on this particular one. you learn something new all the time.
Thank you Pyrrhula. thisone was transplanted and therefore I was surprised that it had one flower..so next year it will be bigger with more flowers I'm sure.
I/we do have the seem flower and colour in our garden 12 flowers,more or less to day