What is the name of the pigment that gives flowers their color?

All flower colors are produced through pigments that occur in chemicals deep in the cells of the plant. The same color pigments that make leaves change color in fall give color to flowers, vegetables and other plants. These pigments are called anthocyanidins. Individual pigments are named for the flowers in which they first were found; the purple petunidin pigment, for example, was found in the petunia. These pigments show through the cells of the flower blossoms and are refracted, the same way prisms refract light. The prismlike effect creates different shades of blue-green, purplish-blue and other combinations.

Some flowers change colors. Forget-me-nots and lungworts bloom pink, then turn blue over time. The phenomenon occurs when flowers have aged past pollination. Weather and temperature conditions also play a part in flower color, making blooms more or less vivid. Cooler garden climates are more likely to have bright blossoms, while warm summer gardens have deeper, duller flowers. Drought, disease and other problems affect the way pigments are produced, and also may affect flower color. Hydrangeas change color depending upon soil conditions; turn the blossoms from blue to pink by lowering aluminum levels in the soil. Change them from pink to blue by adding aluminum.