Velcro petals help bees stick to flowers

By Terri Russell 22 June 2012
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Cone-like projections on flowers act like Velcro to help bees stick to petals in strong winds, new research shows.

FLOWERS HAVE EVOLVED Velcro-like petal surfaces to help bees grip in the breeze, a new study has revealed.

Conical cells on the petals allow bees to maintain a foothold if they’re shaken around on blustery days.

“As the world faces pollinator decline, colony collapse disorder and the increasing need for greater global food production, it is more important than ever to understand this fundamental process [of pollination],” says Australian botanist and researcher Katrina Alcorn, who’s currently working at Cambridge University in the UK.

Velcro petals help bees stick to flowers

It’s already known that most flowers have cone-shaped cells on their petals and that bees prefer them to flat-celled surfaces, says Katrina, but scientists didn’t know why.

This study shows that plants have developed conical cells to help bees battle windy conditions, Katrina says.

“This trait, present in the majority of flowering plants, is an adaption to weather conditions that would otherwise cause bees to be unable to forage, or to need to expend much more energy to gain the same resources,” she says.

Even flat, opened shaped petals that would otherwise be easy for bees to land on, have been found to have these cells.

“When flowers move in the wind, even simple flowers are difficult for a bee to hold on to,” Katrina says. But with increased grip, “bees can take more of their hard-earned nectar back to the colony.”

Synergy of bees and plants

In the new study, bees were offered the choice of a normal plant – in this case a petunia – and a mutant strain without conical cells.

When there was no wind, the bees preferred brighter, flat-celled flowers over duller flowers with conical cells – rendering colour more important to bees than grip.
However, when a ‘shaking platform’ was used to mimic the way flowers move in the wind, the bees began to prefer the conical-celled flowers, regardless of colour.

“From these results we can conclude that cone-shaped surface cells are important, even in simple flowers, because they help bees to grip the petal in windy conditions,” says Katrina.

Dr Katja Hogendoorn, an ecologist from the University of Adelaide says it is “obvious” the conical cell structures have evolved for the benefit of pollinators.
“Conical cells both influence the reflection of the flower and give bees and other insects a foothold,” says Katja.

Furthermore, the shape of the cells differs between flowers that are pollinated by bees and those targeted by birds.

Velcro flowers could be used in crop production

Katja says the study could potentially be used in agriculture and crop selection, although there is still more research to be done.

“There is a long way to go before we can start acting on [agricultural improvements],” Katja says.

Katrina and her team are now investigating pollination of plants that don’t have conical cells and the presence of the gene in non-flowering plants like moss and liverworts.

The findings were reported in the journal Functional Ecology last month.