The bee orchids: Aggressive Mimicry

Possible the most remarkable form of mimicry in the plant kingdom is that found in the genus Ophrys, the bee orchids. . The flowers of these orchids have evolved to mimic the appearance of a bee or wasp and the plants use three means to fool insects. First, the lower petal, known as the labellum, bears a remarkable resemblance to a bee in size, shape and coloration, Second, the flower does not stop at just using visual signals to attract insects; it also use tactile stimuli, with the presence of hairs on the sides of the labellum. Third, the flower has evolved to produce fragrances that mimic sex specific pheromones for particular species of bee or wasp. Thus, there are a lot of different shapes of flowers to attract different insects.

The flowers attract the insects using visual, tactile and olfactory stimuli. The plant fools the male bees or wasp into believing the flower is a female. The male then try to copulate with the flower which involves the insect brushing against the pollinia of the flower. So, the frustrated insect visits other flowers and the pollen is transferred. 

It is awesome. A lot of scientists are studying how this process started. That evolutionary feature might be a decisive aspect to keep this genus alive. However, this type of mimicry causes some problems. The relationship can become so specific. Then the flower depends on the insect to reproduce. If some problem occurs with the insect the flower may be extinct. 

Look that video which show more details about these wonderful plants! 

Reference

Scott, P. 2008, Physiology and Behaviour of plants, 1st edn, Wiley: USA

Video viewed 11 May 2014:

You tube: https://www.youtube.com/watch?v=-h8I3cqpgnA

A particular group: Passionflowers

Plants use various methods to avoid their predators. In today's case, we'll meet another example of aggressive mimicry in passionflower species. Heliconius butterfly larvae is the fiercer predator of passionflowers plants. Also, these insects lay their eggs on the leaves of passionflowers plants. However, they do not lay their eggs where has eggs from other Heliconius butterfly. So, that plant found a way to deceive these predators. Around 2¢ of passionflower plants have evolved pigment protuberances on the structure of the plant (Figure 1)  that mimic Heliconius egg. So, the butterfly by-pass the plant because it saw structures that seems like eggs and they do not lay there. These structures are found on the stem and leaves. 

 Figure 1: Passionflowers plants with pigment protuberances 

Curiosities: Besides mimics, these plants use other mechanisms. An interesting mechanism is found in Passiflora foetida (Figure 2). That plant evolves an odour (smell) which fools butterflies onto believing that the plant is unfit or rotting. As a result, the butterflies avoid them.

Figure 2: Passiflora foetida

Other interesting mechanism is found in Passiflora suberosa that has a lot of different types of leaf shapes that make the butterflies do not recognize the plants. 

Reference

Scott, P. 2008, Physiology and Behaviour of plants, 1st edn, Wiley: USA

Figures viewed 04 May 2014:

Figure 1:http://commons.wikimedia.org/wiki/File:Foetid_passionflower_%28Passiflora_foetida%29_%286128013446%29.jpg

Figure 2: http://adarwinstudygroup.org/biology-culture-psychology/mimicry/