Plants are wonderful and full of surprises. For instance, why do some plants have different coloured flowers? The pulmonaria blooms, as far as I can tell, are different colours no matter how old the bloom is. Makes for a very pretty display.
This Virginia bluebell has very pink buds that turn very blue on opening,
but right beside it is a plant that is all pinky purple. The two plants were the same colour as each other last year. I suppose, as it is with hydrangeas, slight differences in the soil could account for the different colours.
Forget-me-nots are traditionally blue but often grow sports that are white or pink. Seed from a white sport will probably give you a blue plant though. Quite intriguing.
The forget-me-not buds are often pink and the flowers turn blue as they open, but the white flowers come from white buds.