Spectacular blooms of flowers spotted in driest place on earth

By Danny Halpin via SWNS

Spectacular blooms of flowers in the driest place on earth and visible from space attract insects with light invisible to the human eye, reveals new research.

Around every five to 10 years between September and November, the Atacama desert in northern Chile bursts into life after abundant rainfall earlier in the year.

Known as the desierto florido, or blooming desert, the natural phenomenon produces a sea of diverse colors, shapes and visual patterns across what is normally a barren landscape.

Stretching for around 1,000 miles along the western coast of the cone of South America, the Atacama is the driest place on Earth.

Some weather stations there have never recorded rainfall throughout their existence.

But when it does rain in other parts of the desert, what follows is truly magnificent.

The plants are pollinated by insects like bees and wasps, known as hymenopterans, and scientists from the Institute of Agricultural Research in La Cruz, Chile, have been studying how they are able to perceive the variation.

Dr Jaime Martínez-Harms said: “Our aim was to shed light on the ecological and evolutionary mechanisms that cause biological diversity in extreme environments like the Atacama desert.

“Here we show that flowers of the pussypaw Cistanthe longiscapa, a representative species for desiertos floridos in the Atacama desert, are highly variable in the colour and patterns they present to pollinators.

"This variability probably results from different so-called betalain pigments in the flower petals.”

Betalains – yellow, orange, and purple pigments – are a typical trait of the plant type Caryophyllales to which the pussypaws belong.

They don’t just give colours to flowers, they also protect from drought, salt stress, and damage from environmental stress – traits highly beneficial in deserts.

Dr Martínez-Harms and colleagues studied a desierto florido event in late 2021 near the city of Caldera in northern Chile.

A dominant species was the Cistanthe, an annual plant that grows up to 20cm high, which bloomed in two distinct patches tens of kilometres across.

These patches consisted of – to human eyes – uniformly purple and yellow flowers and between them grew numerous reddish, pinkish, and white flowers of the same species, suggesting that the purple and yellow are variants that can interbreed.

However, insects, with their compound eyes and different sensitivities, see the world very differently than humans.

Most hymenopterans have three types of photoreceptors in their eyes, which are sensitive to UV, blue, and green.

Dr. Martínez-Harms and his team used cameras sensitive to visible light and UV and spectrometers to measure how 110 purple, yellow, red, pink and white Cistanthe flowers reflect, absorb and transmit different wavelengths.

This allowed the scientists to produce composite images of these variants as seen by the hymenopterans that pollinate them.

The results show that just within this single plant species, the diversity perceptible to pollinators was greater than to us.

Like us, hymenopterans can distinguish between red, purple, white and yellow, but they can also distinguish between a high and a low UV reflection among purple and yellow flowers.

A UV bullseye pattern at the heart of some flowers guides pollinators to the nectar and pollen, which is invisible to us.

An exception is the UV-reflecting reddish and pink variations, which humans can differentiate between but probably look similar to hymenopterans.

The researchers suggest that the variety of Cistanthe flowers is driven by the preference for different colours and patterns between various species of pollinators.

Dr. Martínez-Harms added: “The great variation in flower colour within Cistanthe longiscapa can be explained if different species of pollinating insects, through their preference for particular flower colours and patterns, could cause these variants to become reproductively isolated from other individuals of the same plant species.

“This ongoing process could ultimately lead to the origin of new races or species.

“In our next studies, we will further investigate the chemical identity and the biological synthesis pathways of betalains and other flower pigments, as well as their relationship to traits such as the scents produced by the flowers.

“This should help us to understand their role in shaping the interactions between plants and their pollinators, and in the plants’ tolerance to biotic and abiotic stressors under fluctuating climate conditions.”

The findings were published in the journal Frontiers in Ecology and Evolution.