Murderous plants strange as fiction

Arthur Conan Doyle, of Sherlock Holmes fame, wrote a story about an American who vanished without trace. Another character, Joe Hawkins, was on the point of being hung for the American’s supposed murder when the victim’s body was discovered, half digested, inside a giant venus flytrap plant.

In the 1950s, John Wyndham took up the carnivorous plant theme in The Day of the Triffids. Wyndham’s murderous plants nearly overran the planet.

The 2000-odd species of real insect-eating plants are almost as bizarre as the fictional ones. These plants catch their prey with pitfall traps, flypaper traps, snap traps and bladderwort traps.

Pitfall traps, otherwise known as pitcher plants, have leaves shaped like small cups.

Insects are attracted in by the scent of nectar but the cup has slippery walls and the prey slips into a liquid containing digestive enzymes.

Hundreds of species of pitcher plants catch insects, spiders and, rarely, frogs, lizards, mice and small birds. Pitcher plants live in the tropics and some growing in Borneo are called ‘‘monkey cups’’ as monkeys drink rainwater out of them.

With flypaper traps, the leaves or stems of these plants trap small insects on their sticky surface. Some flytrap plants dissolve and absorb the insects where they are stuck, others trap flies whose bodies rot on the plant before falling off. Nutrients in their bodies impregnate the soil and the plant’s roots suck up these goodies. The best-known flypaper traps are the sundews that get their nitrates and phosphate nutrients from the animals they trap.

The best known of the snap traps are the venus flytraps. The surface of their leaves is very sensitive to touch and spring shut to trap insects and spiders. Surprisingly these plants have a simple memory, as they learn not to respond to raindrops after a few fall on their sensitive leaves.

Bladderworts grow in boggy places, if not actually in water. Their roots have bladder-like traps that suck in and digest tiny water insects.

Dr Kenji Fukushima recently found that carnivory has evolved separately in six kinds of plants and all six have independently invented the same genetic recipe for absorbing the insect nutrients. He has yet to look into some insecteating fungi.

New Zealand has its insectivorous plants. We have seven native honeydews (drosera), and three bladderworts (utricularia). A few foreign insecteating plants that have also set up home here.

We also have our own New Zealand Carnivorous Plant Society. The society runs spring and autumn shows in many cities and publishes a quarterly journal now on its 96th issue.

The society’s tentacles stretch into some far corners. Online you can buy shirts depicting bugs fighting carnivorous plants. Auckland’s Mexican Carnivorous Plant Society Band plays multiinstrumental sci-fi music.

Some society members are drawn to comics and animations of novel length. In some, characters from Melting Faces and Fanthom Finger stories are sucked down holes and repeatedly eaten and regurgitated by ugly plants.

Move over Doyle and Wyndham.