The orchid is one of the most unique and instantly recognisable flowers in the world. It has evolved a so-called lip - a large and irregular modified petal, to attract insects - but the driving force behind this unusual shape was not known, until now. Researchers have found that its shape is determined by two competing groups of proteins and by tweaking them, they can convert this lip into a standard petal. The orchid (an example of which is pictured) has evolved a so-called lip - a large and irregular modified petal, to attract insects - but the driving force behind this unusual shape was not known, until now . The study, published in the journal Nature Plants, extends scientists' understanding of the mechanisms leading to the diverse beauty of orchid flowers. There are between 21,950 and 26,049 accepted species of Orchid, most of which have a large and irregular modified petal, called the lip, in addition to three 'normal' petals. The structure of orchids is unique among floral plants. They also have three sepals, which sometimes look like other petals, and a single column at the centre which is used during reproduction. Researchers have found its shape is determined by two competing groups of proteins. They converted lips into petals in two orchid species by reducing the activity of the L complex using gene silencing (illustrated) Conversion of lips into sepal/petal-like structures in Oncidium and Phalaenopsis orchids is shown . Orchids have three sepals, which sometimes look like other petals, and a single column at the centre. Lips attract insect pollinators and serve as a landing platform for them, which is thought to have given orchids an evolutionary advantage over other flowers, by promoting reproduction. To discover why the flowers developed their distinctive lips, researchers  from National Chung Hsing University in Taiwan studied the expression of a class of genes known to be associated with petal development. They found that in mature orchid flowers, the expression pattern suggests two protein complexes, called the 'L' complex and the 'SP' complex, compete to promote the formation of the lip and standard petals. The have called this mechanism the Perianth code and discovered that orchid species from many subfamilies with different types of lips and petals all obey it. The experts were also able to convert lips into petals in two orchid species by reducing the activity of the L complex using gene silencing. Lips attract insect pollinators and serve as a landing platform for them, which is thought to have given orchids an evolutionary advantage over other flowers, by promoting reproduction. Lips are differently coloured, ruffled or pouch-shaped, depending on the species, and can be decorated with horns, hairs, warts, teeth and tails to attract specific pollinators. These range from bees to flies, gnats, moths, butterflies, hummingbirds and even bats in some tropical climates. To discover why the flowers developed their distinctive lips, Chang-Hsien Yang and his colleagues from National Chung Hsing University in Taiwan studied the expression of a class of genes known to be associated with petal development. They found that in mature orchid flowers, the expression pattern suggests two protein complexes, called the 'L' complex and the 'SP' complex, compete to promote the formation of the lip and standard petals. The have called this mechanism the Perianth code and discovered that orchid species from many subfamilies with different types of lips and petals all obey it. The experts were also able to convert lips into petals in two orchid species by reducing the activity of the L complex using gene silencing. The scientists studied the expression of a class of genes known to be associated with petal development. They found that in mature orchid flowers,  two protein complexes, called the 'L' complex (red) and the 'SP' complex (blue), compete to form the lip and petals. This competition and balancing act is illustrated above . The pastel-coloured orchid mantis has fascinated naturalists for more than a century. It was popularly thought that the insect, whose legs are flattened and heart-shaped to resemble petals, simply mimics an orchid, allowing it to 'hide' and catch prey. But earlier this year, scientists suggested that the mantis doesn't simply blend into flowers, but is attractive to insects in its own right, sometimes preferring to remain more easily visible on leaves. It was popularly thought that the orchid mantis (pictured), whose legs are flattened and heart-shaped to resemble petals, simply mimics an orchid, allowing it to 'hide' and catch prey . Dr James O'Hanlon of Macquarie University, Australia, set about systematically testing the ideas contained within the traditional view of the orchid mantis' modus operandi. First, his team tested whether mantises actually camouflage among flowers, or, alternatively, attract insects on their own. For a flower-seeking insect, as predicted, the mantis' colour pattern is indistinguishable from most common flowers. However, when paired alongside the most common flower in their habitat, insects approached mantises more often than flowers, showing that mantises are attractive to insects by themselves, rather than simply camouflaging among the flora. 'We can clearly observe insects, like bees, diverging from their flight paths and flying right towards this deceptive predator,' Dr O'Hanlon said. When paired alongside the most common flower in their habitat, insects approached mantises more often than flowers, showing that mantises are attractive to insects by themselves, rather than simply camouflaging among the flora. Here, an orchid mantis eats a Tiger heliconian butterfly in Malaysia . They also found that mantises did not choose to hide among the flowers, but selected leaves to sit on, just as often. Sitting near flowers did bring benefits, though, because insects were attracted to the general vicinity. When they compared the mantis's shape and colour with flowers from an insect's perspective, the predator did not resemble an orchid or indeed any particular species of flower, but rather a 'generalised' flower. They may exploit a loophole created by evolutionary efficiency savings within the insect brain. The compact brains of insects use a rule of thumb - anything matching colour X is a nectar-containing flower – and the predator uses 'sensory exploitation' to catch its victims. Sensory exploitation is a concentrated mass of the right colour. The insect classifies the mantis as a giant nectar-filled flower and approaches to investigate – to its doom.
Orchid has evolved a 'lip' - irregular modified petal - to attract insects .
Researchers in Taiwan found its shape is determined by two competing groups of proteins - the 'L' complex and the 'SP' complex .
By tweaking them, they can convert the lip into standard petals again .