Carnivorous plants: Not just science fiction

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John Wyndham’s classic novel, The Day of the Triffids, is one of my favourites.

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It is about man interfering with nature and nature striking back. The plot’s essence is that man has harnessed a plant called a triffid, named for its three “feet” with which it is able to haul itself out of the ground and walk to find better soil in which to grow.

All is well, until a meteor shower bathes the Earth with light that renders people blind. Of course, the hero manages to escape by becoming blind, ironically due to a triffid sting on his eyes that keeps him from seeing the meteor shower.

The story is about the eventual takeover by the triffids and man’s response to the threat.

It has an ending that can be read however one wants but it is still a rattling good yarn.

While a work of fiction, the novel contains plausible elements – particularly carnivorous plants. While the idea sounds strange, carnivorous plants are yet another example where evolution has solved a problem for life.

In this case, most carnivorous plants grow in poor soils or in swampy areas that are low in nitrogen and phosphorus, two elements they need. While devoid of these elements, the soil is home to a rich source of just the right kind of chemicals – insects. These creatures are like nutrient oil tankers to plants. But how to exploit this resource?

Many plants have evolved the means to trap, kill and digest insects that visit them looking for food. This involves multiple strategies.

First, the plant must attract the insects with bright colours, fragrance and often nectar, which is usually put in a place that requires the insect to crawl deep within the plant to feed.

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Next the plant needs the ability to trap its prey. There are several mechanisms used by carnivorous plants, such as sticky leaves that fix the bug so that it can be processed. Some plants use slippery leaves to cause insects to fall into a pool of water or other liquid where they are trapped. Perhaps most ingenious is the Venus flytrap, which has a small cage that is triggered when the insect touches small hairs that cause the plant to quickly close a trap around the insect.

Now the third element comes into play – digestion. Carnivorous plants secrete enzymes that slowly dissolve the insect, releasing the constituent chemicals within the bug. These chemicals are then brought into contact with specialized cells that transport the nutrients through the wall of the leaves. This is unusual because most plants only take nutrients through their root systems, but carnivorous plants can manage this trick through specialized leaves.

There are some 800 species of carnivorous plants that deploy these strategies to survive in poor growing conditions. Pitcher plants, sundews and the like are passive hunters, who wait for prey to fall into their pools of digestive enzymes or have glue to trap the happy bug while the juices do their grisly work.

Make no mistake, these plants have a winning strategy.

Insects are rich in the chemicals plants need and cannot get from the soil. A single insect can keep a plant alive for several weeks. And the capture and digestion of several insects allow the plant to grow more traps and to reproduce more often.

While a trope of science fiction, carnivorous plants are not complete fantasy. Carnivorous plants exist by the millions and make a good living by turning the hunting strategy of animals to their advantage.

Now, if I learn there are large carnivorous plants that have developed the means to walk, it may be time to think about leaving the planet for some place safer.

Tim Philp has enjoyed science since he was old enough to read. Having worked in technical fields all his life, he shares his love of science with readers weekly. He can be reached by e-mail at: tphilp@bfree.on.ca.

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