Why Are Flowers So Colorful?
Excerpted From: What Makes Flowers So Colorful?
Plants get their colors from pigments it produces. These pigments are molecules that selectively
absorb or reflect certain wavelengths of light. The wavelength it reflects is the color we perceive.
There are a myriad plant pigments, but we can largely categorize them into four different types.
The color that you see in flowers is actually the result of reflected light from the pigments.
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A flower’s pigments help to attract possible pollinators, such as honeybees, butterflies and
hummingbirds. There are two major classes of flower pigments: carotenoids and flavonoids.
Carotenoids include carotene pigments (which produce yellow, orange and red colors).
Usually, the color a flower appears depends on the color of the pigments in the flower, but this
can be affected by other factors. For example, blue cornflowers have the same pigments as red
roses, but the pigments in the cornflower petals are bound to other pigments and metal ions,
making cornflowers look blue.
The color of a flower is decided by the hereditary genome of the plant to which it belongs. Plant
DNA creates enzymes that catalyze changes to the various molecules, creating flower colors.
The most popular and the most common pigment in plants might be chlorophyll, providing plants
with their green color. Most chlorophylls absorb red and blue wavelength light, mostly reflecting
green wavelengths. And that’s what we see. Chlorophylls, though a plant pigment, aren’t commonly
found in flowers. Their place lies in leaves and stems.
The second group broadens our plant pigment palette, introducing yellows, oranges and red into
it. Carotenoids are the same pigments that impart color to carrots (hence the name), tomatoes,
and sunflowers. A common carotenoid, ß-carotene gives sunflowers its optimistic yellow. It
primarily absorbs light in the blue region of the visible spectrum, giving us a sunny yellow.
The exciting reds, purples, blues and pinks are the result of anthocyanins. These pigments belong
to a class of flavonoids, and are the most important plant pigments for flower coloration. Flavonoids
are a large group of compounds, scientists have discovered over 9000 different flavonoids, which
are responsible for a range of colors.
Anthocyanins are the molecules that give petunias and orchids their enticing pinks, lends the
lilac color of common lilacs, gives roses their passionate reds, and colors blue cornflower, well,
blue. A type of flavonoid, tannins, also give tea its brown color.
Betalains color flower petals red to red-violet colors. These pigments give opuntia (or cactus pear)
its red color and beets its beet reddish-purple shade. They replace nature’s popular pigments,
anthocyanins, in Caryophyllales which include carnations, beets, cacti, amaranths and even
some carnivorous plants.
Just like painters mix colors to create a unique hue, the color of many flowers are a result of a
combination of pigments in different proportions. This creates gradients and patterns within the
These pigments are chemicals, and their color imbuing capacities can be changed by the pH,
association with certain minerals such as iron or magnesium, and temperature. An interesting
example of this is the coloration of roses and blue cornflower. The colors of both the flowers are
caused by the same anthocyanin, the red and the blue. Research has found that the blue is the
result of a ‘superstructure’ of 6 pigment molecules associated with magnesium, iron, and calcium
ions. This is fascinating color manipulation!
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