Name That Flower II

Here's another chance for my loyal readers to help educate me. I shot the flowers above at Stump Pass Beach State Park this weekend. These blossoms were on a large bush, well, almost a small tree. There were more white blossoms than purple, but there were plenty of each color on the same stems. I think I've seen one other bush like this in my travels, but I can't remember where that was. If you have any idea what sort of plant this is, please drop me a line.