So as it turns out, the flowers just smelling and looking pretty for us to enjoy. Apparently there is an ulterior motive for their bright and interesting colours, not to mention their attractive scents. In fact, not only is their scent not for us, it’s not for anything but themselves. It’s true, their lavish colours and smells are intended for one purpose only; to attract various insect pollinators in order to make it easier for the plants to reproduce through pollination.

Studies recently published in The American Naturalist have shown that a small group of plants angiosperms have adapted to interfere with the perceptions –both visually and in other manners- of certain insect varieties. This is achieved through not only visual mimicry, but also the use of specific scent compounds that mimic the select species sex pheromones (Ellis 2010). Angiosperms are the group of plants that include flowers and plants that produce fruits which contain seeds. The male part of the plant is the pollen, and the female part of the flower is the stamen.

It is unclear as to what factors have caused the found result in the number of deceptive plants, since such species usually have fewer visits from pollinators as compared to non-deceptive species. This is because in the case of plants that trick the insects by using colours or scents, the insects temped by their senses quickly discover that the plant is not what is seems and will spend much less time on it (Ellis 2010). Nonetheless, by the point the pollinators have discovered their mistake and have pounced on the plant, thereby depositing pollen on the plant and taking some from the new plant, inadvertently helping the species pollinate (Ellis 2010).

The study, conducted by Dr. Allen Ellis and Dr. Steven Johnston suggests that sexually deceptive plants –meaning the angiosperms that give off sex pheromones similar to that of the specific pollinators they seek to attract, and in some cases visually imitate the insects they are trying to attract- evolved from food-deceptive varieties because of the fact that the sex-driven behaviour of the insects was more beneficial to the flower than food-deceptive behaviour (Ellis 2010). This is because when the pollinators receive food rewards from the flower this causes the plant damage, while the behaviour from the sexual exploitation of the insect left the plant undamaged (Ellis 2010).

In addition, in a group of European and Australian orchids it was shown that the plants that used sexual deceptive techniques had more pollen reach stigmas than the plants who used food deceptive techniques. It was shown that the sexual exploitation by the flowers of male bees and wasps led to long distance pollination, increasing the value of offspring (Ellis 2010).

Some flowers do not offer merely one type of deceptive behaviour though, but both sexual and food-deception. A prime example of this is the daisy, named Gortia diffusa, of which “diffusa” quite fittingly means “outspread” in Latin. The name is suiting of the flower whose long petals are brightly coloured and quite often contain insect-like decorations, attracting many insects such as the bombyliid fly, Megapalpus capensis (Ellis 2010). This species of fly appears to be attracted not only to the species of flowers’ petal spots, but also the nectar the plants offer. An interesting observation however was that the spotting on the daisy’s petals varied from plant to plant and even from individual to individual (Ellis 2010).

Although many plants use food to encourage animals and insects to pollinate them and spread their seeds, some use other methods like sexual deception. These mimicking flowers encourage mating behaviour in the insects that pollinate them, which in some cases has been strongly supported to be as, if not more effective than the food-exploitive behaviours of other plants (Ellis 2010). These deceptive behaviours seem to be geared towards specific species of insects. An example of this is the daisy, which attracted the bombyliid fly more often than other insects on average. Coincidence? Scientists think not.

Article: Ellis, Allan E., and Steven D. Johnson. "Floral Mimicry Enhances Pollen Export: The Evolution of Pollination by Sexual Deceit Outside of the Orchidaceae." The American Naturalist 176.5 (2010). The American Naturalist. Web. 13 Oct. 2010. .

Image: http://www.phenomenica.com/2009_12_01_archive.html