Living color

Desierto florido: What causes these rare flower blooms in the world’s driest desert?

The Atacama Desert presents bursts of colorful flowers every few years.

Oven Pérez-Nates
For most people, the word “desert” probably conjures similar images:

Barren wastes dotted with cacti, maybe a lizard darting from rock to rock.

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But deserts hide plenty of life, and at least in one desert, that life bursts into vibrant view once every few years.

The Atacama desert in Chile

is the driest nonpolar desert in the world. It’s so barren that NASA has used it in tests to simulate the surface of Mars.

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But in years with enough rain, it plays host to the desierto florido, or desert bloom, a phenomenon that briefly turns its arid sands into a patchwork of color that’s visible even by satellites.

European Union, Copernicus Sentinel-2 imagery

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The desierto florido occurs roughly every five to ten years between September and November, carpeting the Atacama desert with multicolored flowers.

During the 2021 bloom,

researchers from Chile’s Institute of Agricultural Research set out to discover what drove the spectacular variation of flowers in such a harsh environment.

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Their findings, published in Frontiers in Ecology and Evolution, found that protective compounds in the flowers’ petals are likely responsible — and that we’re only seeing half of the remarkable show.

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The researchers studied pussypaw Cistanthe longiscapa flowers, one of the most common in desert blooms. To human eyes, the pussypaws appear mostly yellow and purple, with smaller red, pink, and white flowers throughout.

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But using a UV spectrometer,

the researchers revealed far more variation. Flowers of the same color may have different UV reflectivity, and many have a “bullseye” at the center that doesn’t register in the visible spectrum.

Solitary wasps and bees do most of the work pollinating the Atacama Desert, and their eyes allow them to see the bloom in all its glory in the UV spectrum.

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Purple and yellow pussypaw Cistanthe longiscapa (family Montiaceae), the object of this study

Different pollinators are drawn to different colored petals, so researchers suspect the flowers evolved such an array of colors to attract a wide range of insects.

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Since a desert bloom lasts such a short time, the flowers would be under a lot of pressure to spread their pollen as far and as quickly as possible.

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As for what gives the flowers their color, scientists say pigments called betalains are to thank.

In addition to coloring their petals, betalains help flowers withstand drought and other stressors in the extreme desert environment.

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First author Dr. Jaime Martínez-Harms says the team will next focus on betalains themselves. They hope to uncover how the compounds are made and reveal more about how they protect plants and attract pollinators.

Oven Pérez-Nates

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