Carnivorous Plants
New Zealand has 12 native species of carnivorous plant – which capture and digest bugs in ingenious ways!
Many carnivorous plants like sunny, wet places with nutrient-poor soil. That often means clay banks, wetlands, and alpine areas. Rather than absorb nutrients from the soil through their roots, they get much of what they need from meat they trap.
They used to be far more common, especially in lowland areas, but now many habitats are spoiled for them.
Wetlands have been drained for farms or development sites, and those that do remain may have farms right next to them. Fertiliser runs from the farms into the wetlands, changing them from nutrient-poor to nutrient-rich environments. Plants that like nutrient-rich enviroments grow vigorously and soon take over.
New Zealand has two types of carnivorous plant – Drosera (commonly called sundews) and Urtricularia (or bladderworts).
Drosera (sundews)
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Sundews have leaves covered in tiny, hair-like tentacles, often red. Each tentacle has a blob of sticky goo on it. If a fly lands on a sundew, it sticks.
The more the fly wriggles, the more it gets gummed up. Then the sundews’s tentacles start to curl around the fly, clutching it tighter and tighter. The goo contains enzymes that digest the fly's flesh so the plant can absorb it.
New Zealand has seven native sundews.
The smallest is Drosera pygmaea, a ‘pygmy sundew’ that grows only about as big as your thumbnail. These catch ants and sandflies.
A spectacular species is Drosera binata, which sends up masses of forking leaves and can grow to a metre tall – about as high as six year old! These catch larger prey.
Sundews are in the same family as the most well known carnivorous plants in the world, Venus flytraps.
Urtricularia (bladderworts)
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Aquatic bladderworts grow in lakes, ponds, even ditches. Terrestrial bladderworts grow in mud.
Above the water or mud, they look almost boring. Below, they set the most complex traps in the carnivorous plant world! Their subterranean parts are covered in small vacuum sacs that have trapdoors.
A bug swimming past triggers a trapdoor. It opens, the bug is sucked in, and the door closes again, all in milliseconds! Inside the trap, the plant releases digestive juices that pulp the imprisoned bug.
New Zealand has two native terrestrial bladderworts, and three native aquatic bladderworts.
Why are carnivorous plants so valuable?
Carnivorous plants offer scientists valuable clues to plant evolution. They can also play a vital role in conservation.
They are ‘indicator species’, so sensitive that pollution and other stresses in their environment make them die off more quickly than many other plant and animals. If they start dying off then this sends an early warning message to an area’s caretakers.
Where do you find carnivorous plants?
New Zealand’s native carnivorous plants still thrive in unspoilt environments such as the Tongariro, Urewera, Arthurs Pass, and Fiordland National Parks.
In the North Island, they also grow in patches around Kaitaia, and in the South Island, in the spectacular landscape of the Denniston Plateau, which is now under threat from coal mining plans.
- Johanna Knox
