I don't know the technical name for it, but I'm looking for flowers and shrubs that change color depending on the soil or some other reason. I think Irises might do this. I'm fairly certain that Hydrangeas change color based on the soil's acidity. Anything else?
No, they don't. It's a controversial topic believe it or not. Some folks will swear that they do and there are different theories for why it happens, but supposedly they don't change color. The cotton rose is a variety of Hibiscus that has flowers that naturally change colors. The blooms start out white, but they eventually turn a lovely pink or red color. They're easy to grow too.
I know irises do not change color, but there are several colors you can choose from. I like the deep purple ones (with the yellow inside). I thought hydrangeas did too. I thought they started white. I know burning bushes do, they turn a bright red.
Hydrangeas can change color when they are growing. I think the key to some shrubs changing color is the ph of the soil. If you can change that, you can change the color of the flowers on the shrub.