If you're thinking of buying flowers for mom this Sunday, beware of nature's seductive marketing. A new study published on-line this week in the Journal of Evolutionary Biology shows that flowers flutter in the wind to be attractive. But this floral advertising is not aimed at mother-loving children. Instead, researchers in the UK suggest, flower "waving" is a hitherto unrecognized way that plants entice insect pollinators.

John Warren, a plant ecologist at Aberystwyth University in Wales, remembers lying on a beach at his daughter's birthday party watching flowers blowing in the wind, when something about the flowers struck him as strange. "If they live in such a windy place, why on earth would they have such long stalks?" he wondered.

After the party, he probed the plant literature and realized that while almost every flower feature -- from spectacular color displays to aromatic scents -- is thought to have evolved to attract pollinators, floral waving was not. Long flower stalks are known to aid in seed dispersal for wind-pollinated plants, but insects were not thought to be swayed by floral movement. Now though, Warren has shown that some plants have evolved fluttery flowers, which may be key to attracting insects.

Warren and his colleague Penri James mounted the heads of British wildflowers called sea campions (Silene maritime) onto artificial wire stalks of different lengths and thicknesses, and measured the frequency and duration of visits by common hoverflies. They found a trade-off: insects visited the more mobile flowers mounted on thin stalks more often, but they visited flowers on thick stalks for longer. Medium-length stems received the most visits at either thickness, and combined measures of mobility suggested that intermediately flexible flowers -- similar to those found in nature -- are the best for attracting insects and allowing effective pollination. Warren also showed that floral stalk mobility is a heritable trait, so intermediate flower "waviness" is probably maintained by stabilizing selection.

"If you're too stationary nothing visits you because you're not visible," Warren told The Scientist. "But if you're too wavy, insects find it hard to hold on and are blown off."

Scientists had observed flower waving before, but had not explored its significance. "If an animal behaves in that way, we would investigate it," said ecologist Anita Diaz of Bournemouth University in England. "But because it's a plant, it was just thought to be waving in the wind, and we didn't think of it as a behavioral trait before." She noted, however, that the paper only shows this adaptive feature in sea campions, and it remains to be seen how universal flower waving is. "I see this as a paper starting a debate, rather than proving a point," she said.

Heather Whitney, a plant biologist at the University of Cambridge, agreed that the study challenges the notion that plants are passive and static. But if flower stems are indeed tailored to the "correct" size, the onus is still on the authors to show that stem length and thickness is correlated with wind speeds in different habitats, she said.