Hydrangea macrophylla
"Hydrangea macrophylla" blooms can be blue, red, pink, light purple, or dark purple. The color is affected by soil pH. An acidic soil (pH below 7) will usually produce flower color closer to blue, whereas an alkaline soil (pH above 7) will produce flowers more pink.This is caused by a color change of the flower pigments in the presence of aluminium ions which can be taken up into hyperaccumulating plants.