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Roses are Red

Roses are Red

Credit: Jason Baker
Source: http://www.flickr.com/photos/mezuni/2085394019/
License: CC BY-NC 3.0

The vivid color of this rose brings to mind an old rhyme. It also brings a bee to the flower, seeking nectar. You know roses are red (and violets are blue), but did you ever wonder how and why flowers have such beautiful colors?

The Back Story

  • What determines flower color? It’s basic chemistry.
  • In fact, chemistry explains why most things have color. In plants, flower cells produce specific color molecules called pigments. Each pigment absorbs most wavelengths of visible light and reflects just one or a few wavelengths.
  • Credit: Misserion
    Source: https://www.flickr.com/photos/misserion/2430082358
    License: CC BY-NC 3.0

    different wavelengths of light result in different colors of flowers [Figure2]

  • The wavelength of visible light determines the color that the light appears to the human eye. So whatever wavelength of light a flower reflects is the color you see.
  • Watch this video to learn in detail why roses are red, violets are blue, and other flowers have their own hue: http://www.nbclearn.com/chemistrynow/cuecard/53149

Show What You Know

At the link below, learn more about color in flowers. Then answer the following questions.

  1. Why are roses red?
  2. Which pigment is most common in plants? What color does it appear?
  3. What are the two types of pigments that make most flower colors?
  4. Why do pigments absorb the light waves they do?
  5. What factors determine the color of a given flower?
  6. How did flower colors evolve?

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Image Attributions

  1. [1]^ Credit: Jason Baker; Source: http://www.flickr.com/photos/mezuni/2085394019/; License: CC BY-NC 3.0
  2. [2]^ Credit: Misserion; Source: https://www.flickr.com/photos/misserion/2430082358; License: CC BY-NC 3.0

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