I recently spotted this weird bloom on my father's rose plant, a Don Juan. The bloom looks really weird. I have never seen a bloom like it before, my mother said it is a stunted bloom (if that is possible, I don't know). My dad says to just wait and see what happens, let it go its course.

I was wondering if anyone had an explanation for it.

--The plant has black spot, but I don't know if that would affect the bloom.

Thank you!