Big question about water lilies

Some time back, I had an entry about the white water-lilies in my pond. I thought that the pH level in the pond had changed the color of the water lilies from other colors to white.


But I was so mistaken as I later found there were some purple blooms in the pond too.


And just today I found another water lily with a yellow-cream bloom!


Now that the purple and yellow water lilies have shown up, I wonder where have those white water lilies come from? I know for sure I threw in some purple and yellow lilies but not white. Big question.