Flowers 'wave' at passing insects to get attention

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Scientists from the University of Aberystwyth made this discovery when they were studying “sea campion,” a wild flower on the Welsh coast. They found flowers that were more mobile were visited more often by the insects and they also produce more seeds than other flowers.

They say the "more mobile" flowers also attract a wide variety of insect species compared to the stationary flower plants.

Scientists have known in the past that flowers use color diversity, fragrances, uniquely shaped flower petals and nectar to attract a wide variety of insects. However, nobody had studied the “waving” effect until now.

John Warren from the University of Aberystwyth, one of the researchers told BBC:

I was lying on the beach watching flowers wave in the wind at my daughter's birthday party, and I wondered why they have stalks and risked getting damaged in such an exposed habitat.

Warren researched further to see whether others had studied this mobility part and how it encouraged insects to visit the flowers more often. However, he could find only one study that determined insects are not good at detecting movements. He didn’t think that conclusion could be true, so he wanted to prove it by studying wild flowers.

He and colleague Penri James studied sea campion (Silene maritime) along the Cardigan Bay in west Wales.

They observed nearly 300 specially grown flowers of varying stem lengths and recorded how much each flower moved in the wind, how often it was visited by insects, how long they stayed on the flower, and how many seeds the flower produced.

They found that flowers mounted on long, thin stalks move more in the wind and this acts as a powerful signal to the passing pollinators, attracting more insects than short-stemmed flowers.

John Warren told BBC:

We found wavy flowers are more visible to insects, and thus attract more pollinators and set more seeds

But there is an evolutionary trade-off as Warren calls it: Short stacks with thick stems don’t wobble enough and thus attract fewer insects, while longer stacks and thin stems wobble too much making it difficult for the insects to land on them. Only the right size stalk and stem are able to attract higher numbers of insects to produce more seeds.

They have reported their findings in the current issue of Journal of Evolutionary Biology.