The curious case of carnivorous plants capturing insects

The Venus fly trap is a popular carnivorous house plant. Picture: Shutterstock.
The Venus fly trap is a popular carnivorous house plant. Picture: Shutterstock.

Carnivorous plants are fascinating.

They have turned the tables on the insect world, where they threaten the hunter with becoming the prey. You can even create your own little shop of horrors with a collection of carnivorous plants in your garden.

Carnivorous plants have adapted to capture and digest insects to provide the nutrients required to sustain their growth. The adaptations to capture insects depend on the species and traps are either passive or active.

Passive traps do not move and rely on luring the insect onto or into the digestive system of the plant.

Active traps move and enclose their prey. For example, the venus fly trap uses an active trap.

It is one plant that will always draw in people's curiosity due to the macabre way it captures its prey.

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As an insect is lured to the sweet smell of nectar secreted from the fly trap's brightly coloured trap, tiny hairs on the surface of the trap trigger the shutting movement.

This is known as thigmotropism, which triggers a movement of the plant parts in response to a physical stimulus. The trap will gradually tighten, squeeze the insect, and secrete digestive acids.

After a few days, the trap will open to reveal the spent exoskeleton of its victim.

Other popular carnivorous plants for home gardens include pitcher plants. These plants trap their victims by enticing them to the edge of the pitcher with sweet nectar; insects lose their grip on the slippery surface of the pitcher's rim and fall into the digestive juices of the pitcher becoming an easy meal. Some tropical pitchers can hold up to two litres of fluid and have been known to digest rats.

Sundews are another interesting group of carnivorous plants with mucous-like globules that extend from the leaves glistening in the sun. These glue-like droplets trap insects that literally put their foot in it. Once stuck the tentacles wrap around the insect making escape impossible.

The most common species of carnivorous plants are bog plants, which detest drying out. They can easily be grown in a self-watering container or a terrarium, where moisture will always be available to the plant. You can grow them in a peat-sand mix, but do not use regular potting mixes with fertilisers.

Full sun and regular moisture is required by most species ... and of course insects.

  • John Gabriele is a horticulture teacher.
This story The curious case of carnivorous plants capturing insects first appeared on The Canberra Times.