What Makes Flowers Colorful?

Flowers bloom in many vibrant colors.

People have long grown flowers for their beautiful colors. But the purpose of flower color isn't visual appeal. Flowers use their color to attract pollinating insects in order to reproduce. The color of flowers is determined by a complex set of chemicals and circumstances. Scientists are experimenting with these chemicals to create new and even more colorful flowers.

Floral Pigments

Floral pigments are plant molecules that absorb some wavelengths of light and reflect others. Which wavelengths these pigments reflect determine the color of the flower. The three main color-producing pigments in flowers are flavonoids, carotenoids and chlorophyll. Scientists have mixed these in varying concentrations and added genes from other plants to produce new colors.

Cellular Structure

In the petals of flowers, cells create prisms of light, bending the light and altering the color of the flowers, giving them varying shades and intensity of color. The pH level of the cells will also affect the color of a flower. This is commonly seen in hydrangeas that can be either pink or blue, depending on the acidity of the soil, and morning glories can change from pink to pale blue.

Perception

Color is interpreted differently by individuals. In general, men see primary colors more vividly, while women see secondary colors. In addition, flowers may appear more vibrant in the early morning and at dusk. The color we see is actually light reflected off the flowers, and more light tends to "wash out" a color.

Plant Health

Healthy plants growing in cool, moist, well-drained soil and free of stress tend to have more colorful flowers. Faded flowers are one the first signs that your plant is not healthy. If your plant's flowers are not as vibrant as usual, check for insect or fungal infestations. Drought, excessive heat and poor nutrition will also rob your flowers of their color.

Age of the Flower

New flowers tend to have more concentrated levels of pigment. As the flower ages, the color tends to fade. This indicates to the pollinating insects which are the prime targets for gathering pollen.

References

• Exploring Nature in the San Francisco Bay Area: Articles: What Makes Wildflowers So Colorful
• The United States National Arboretum: Cracking Nature's Color-Code for Flowers.
• University of Vermont Extension: Color in Flowers
• Changing the color of Hydrangeas