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Tuesday, December 22, 2009

Deceptive Beauties

Orchids are beautiful flowers known for their trickery. Unlike most flowers, which lure their pollinators with nectar rewards, orchids often use deception, producing flowers that look or smell like female insects.
At first glance, this approach seems limiting. After all, nectar will lure a much greater variety of potential pollinators than will a come hither signal which will only lure one species, and only males at that. So why have so many orchids adopted this strategy?

Researchers Salvatore Cozzolino and Giovanni Scopece of the University of Naples Federico II, Steven Johnson of University of KwaZulu-Natal (South Africa) and Florian Schiestl of the University of Z├╝rich have published their conclusions.
If a bee is looking for nectar and pollen, she may visit any number of types of flower. After her first visit, the second flower she visits may also be from a variety of species. The second flower gets no benefit unless the prior flower happened to have been from the same species.
In the case of the orchid, the flowers attract only one type of bee or wasp, a male looking for a mate. When that frustrated bee leaves the first flower, chances are very good that the next flower he selects will be of the same species.
In other words, although fewer overall pollinators may alight on an orchid, those that do will preferentially transfer the right kind of pollen. And ultimately, that’s all the flower cares about.
Ophrys apifera, a type of Bee Orchid, by Hans Hillewaert, 3/06/2008