The deceptive evolutionary strategies of Wild Orchids

As you walk across a wild flower meadow or through pristine forest, the sight of an orchid, be it pink, speckled, green, or one of the other range of colours and designs these strange plants can appear in, will likely bring a smile to your face. But what you may not realise is how this family of plant shrewdly and cunningly manipulates members of the natural world to do its bidding.

No Nectar?

Nectar is a sweet, sugary substance that is produced in the flowers of many plants through the use of glands called nectaries. Nectar, unlike pollen, serves no purpose to the flower, other than as a way of attracting animals such as bats and bees towards them. As these animals feed on this rich source of nutrients, many inadvertently end up carrying the pollen that is also held by the flower, and after leaving and travelling to a different plant of the same species, allow it to be spread, and giving the plant the ability to reproduce and create more of its own kind. However unlike most plants, no orchid in existence produces nectar. Therefore rather than being able to partake in this mutualistic relationship with animals, many orchids resort to releasing pheromones that mimic the scent of nectar. This leads to insects and other organisms visiting the flower in search of food, and coming into contact and spreading the pollen they carry, while gaining little from their exertion of time and energy.

Sexy time? You wish

The necessity of food is what drives many creatures to be fooled by the sly tricks of orchids. However, sex is also a necessity, as animals are evolutionarily driven to mate and reproduce, and orchids have greatly used this to their advantage.
The Bee Orchid (right) has evolved to mimic the appearance and the scent of female bees of the genus Eucera. When males become attracted to the bee imposter, they attempt to mate with it and gain a pollen packet (sticky package of pollen that can attach to anything it touches). Once they move on, they become attracted to yet another bee orchid that they will attempt to mate with, bringing the pollen packet they are carrying into contact with it, and initiating reproduction between the flowers.

You go where I tell you to go

Another way Orchids manipulate mobile creatures is by controlling their movements once they land on their flowers. As you may have noticed, orchids tend to have strange physical shapes and internal compartments. This evolved as a way of leading bees, and other small creatures to the correct area of the flower, for them to be able to come into contact with pollen. For example, Lady Slipper orchids (left) are attractive to miner bees. If  a miner bee ever enters this species of orchid through the opening pictured, it can become trapped within an internal compartment unable to escape back through the way it came. That is only until it chooses a different direction, crawls through a narrow groove formed from a particular fused area of the flower, travels past the stigma, and makes contact with the pollen filled sacks, can it then find the exit and escape; now carrying a lot of flower DNA that needs to be spread far and wide.

Orchids are beautiful, mesmerising, and wonderful plants, and many people are dazzled when catching sight of them. But as is common in the natural world, the majority of biological organisms have lives that are far more exciting, thought provoking, erratic, and in this case manipulative, than may be originally believed.

-Thomas Glen

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