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<H1 id=news-article-heading><FONT size=3><EM>University of
Bristol</EM></FONT></H1>
<H1>Blowing in the wind: how hidden flower features are crucial for bees</H1>
<P id=news-article-date class=news-article-date-effective><STRONG>Press
release</STRONG> issued 29 May 2012</P><!--Lead in--><!--Start content-->
<P>As gardeners get busy filling tubs and borders with colourful bedding plants,
scientists at the Universities of Bristol and Cambridge have discovered more
about what makes flowers attractive to bees rather than humans. Published today
in the <A href="http://www.britishecologicalsociety.org/">British Ecological
Society's</A> journal <EM><A
href="http://www.functionalecology.org/view/0/index.html">Functional
Ecology</A></EM>, their research reveals that Velcro-like cells on plant petals
play a crucial role in helping bees grip flowers – especially when the wind gets
up.</P>
<P>The study focuses on special cells found on the surface of petals, whose
stunning structure is best seen under an electron microscope. According to lead
author, Dr Beverley Glover: “Many of our common garden flowers have beautiful
conical cells if you look closely – roses have rounded conical petal cells while
petunias have really long cells, giving petunia flowers an almost velvety
appearance, particularly visible in the dark-coloured varieties.”</P>
<P>Glover's group previously discovered that when offered snapdragons with
conical cells and a mutant variety without these cells, bees prefer the former
because the conical cells help them grip the flower. “It's a bit like Velcro,
with the bee claws locking into the gaps between the cells,” she explains.</P>
<P>Compared with many garden flowers, however, snapdragons have very complicated
flowers; bees have to land on a vertical face and pull open a heavy lip to reach
the nectar so Glover was not surprised that grip helps. But she wanted to
discover how conical cells help bees visiting much simpler flowers.</P>
<P>“Many of our garden flowers like petunias, roses and poppies are very simple
saucers with nectar in the bottom, so we wanted to find out why having conical
cells to provide grip would be useful for bees landing on these flowers. We
hypothesised that maybe the grip helped when the flowers blow in the wind.”</P>
<P>Using two types of petunia, one with conical cells and a mutant line with
flat cells, Glover let a group of bumblebees that had never seen petunias before
forage in a large box containing both types of flower, and discovered they too
preferred the conical-celled flowers.</P>
<P>They then devised a way of mimicking the way flowers move in the wind. “We
used a lab shaking platform that we normally use to mix liquids, and put the
flowers on that. As we increased the speed of shaking, mimicking increased wind
speed, the bees increased their preference for the conical-celled flowers,” she
says.</P>
<P>Dr Heather Whitney from the University of Bristol, and one of the co-authors
on the paper, says that new ways of looking at the interactions between plants
and pollinators are showing the ways in which plants can enhance their own
chances of being pollinated by helping their pollinators forage more
successfully. "Having to land on a moving surface will increase how difficult it
is for bees to forage. By giving their pollinators a surface that increases
their grip, flowers are helping both their pollinators and in the long-run also
themselves."</P>
<P>Katrina Alcorn, <A
href="http://www.bristol.ac.uk/biology/people/heather-m-whitney/index.html">Heather
Whitney</A> and Beverley Glover (2012). 'Flower movement increases pollinator
preference for flowers with better grip', doi: 10.1111/j.1365-2435.2012.02009.x
is published in <EM>Functional Ecology</EM> on Tuesday 29 May 2012.</P>
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