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Question What causes flowers to have different colors?

Answer

Anthocyanins and carotenoids… plus some other things.

Dahlias in Ben Burnside’s Garden. Terry Eiler, photographer, 1997. Coal River Folklife Collection, American Folklife Center,?Library of Congress.

Flowers come in all shapes and sizes, but what makes them truly stand apart from each other is their vibrant colors.? These colors are made up of pigments and, generally speaking, the fewer the pigments, the lighter the color.? The most common pigments in flowers come in the form of anthocyanins.? These pigments range in color from white to red to blue to yellow to purple and even black and brown.? A different kind of pigment class is made up of the carotenoids.? Carotenoids are responsible for some yellows, oranges, and reds.? (These little guys are what cause the brilliant colors of autumn leaves!)? While many flowers get their colors from either anthocyanins or carotenoids, there are some that can get their colors from a combination of both.

Flower Farm in West Suffield, Connecticut. Carol M. Highsmith, photographer, 2011. Prints & Photographs Division, Library of Congress.

Anthocyanins and carotenoids are the main sources of flower coloration, but there are other factors that can affect how colors present themselves.? The amount of light flowers receive while they grow, the temperature of the environment around them, even the pH level of the soil in which they grow can affect their coloration.? Another factor is stress from the environment.? This stress can include a drought or a flood or even a lack of nutrition in the soil, all of which can dampen the coloration of flowers.? And then, of course, there is the visual that the eye and brain form together: humans can, for the most part, view all colors in the visible spectrum, BUT every human perceives color differently, so a red rose may appear more vibrant to one person while it appears more muted to another.? Beauty (and color!) is in the eye of the beholder.

Sunflowers in Wisconsin. Carol M. Highsmith, photographer. Prints & Photographs Division, Library of Congress.

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