What is the most amount of sunflowers on one stem?

I do not think Sunflowers in general have a known maximum number of flowers. Most have one main flower and several smaller ones. ---- It depends on what kind of sunflower you have. I grow ones that have many smaller blooms. Other kinds just have one GIGANTIC bloom. There are also different colors and stuff. (e.i burgundy.) Hope it helps... RangerZ