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AFTER being inspired by the sight of a Catasetum orchid with a metallic-green male orchid bee hovering nearby (see page 24), Christian Ziegler decided to record the ravishing beauty of these flowers. This is no small undertaking. The 25,000 or so species can be found on every continent, that nourish them with carbohydrates.
The result of his endeavours can be seen in , which the biologist-turned-photographer says 鈥済ives a truly global perspective鈥� on one of the biggest, most diverse families of flowering plants.
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Pictured on the left is a flying duck orchid, Paracaleana nigrita, from Denmark in Western Australia, which uses sexual deception to attract male wasps. The insects attempt to mate with a part of the flower that is shaped like a female wasp.
Once the wasp is inside, a sophisticated mechanism catapults it onto the reproductive parts of the orchid. In doing so, the wasp brushes past sticky bundles of pollen, called pollinia, which become attached so that it can fertilise the next orchid it visits.
From an evolutionary perspective, the strategy of relying on sexual displays that only attract the males of one species may at first seem less effective than alternatives. For example, orchids that offer nectar or mimic food could attract a wide variety of food-seeking pollinators 鈥� bees, wasps, flies, ants and so on.
Despite the potential drawback of depending on one pollinator, sexually deceptive orchids have a higher 鈥減ollen transport efficiency鈥� than species with multiple pollinators, according to a study of 31 species carried out by Salvatore Cozzolino and Giovanni Scopece of the University of Naples Federico II, Italy, and colleagues (American Naturalist, ).
Perhaps that is why luring a specific pollinator with the promise of sex has evolved several times in different kinds of orchid.