Who do you barrack for: the hunter or the prey? The leopard or the gazelle? The frog or the snake? The fly or the flytrap? Enter the glittering and sensual world of plants with a thirst for blood.

Share The big bee-looking fly is the prey, and that little bug is going to 'help' the plant digest it.

Homicidal greenery

Share This hanging swamp is home to thousands of carnivorous plants.

The hanging swamps of the Blue Mountains waterfalls plunge off cliffs so high, with winds so gusty, that the water rarely hits the ground. Lining the rock face is the most impressive display of carnivorous Drosera binata in the world.

At any given moment there are hundreds of thousands, or more, insects drowning on this cliff face.

They are being consumed alive in their very own hellish little shop of horrors by this waving ocean of Drosera binata.

Bright, sparkling, green lines streak across the precipice, formed from thousands of the Drosera's V-shaped leaves. Each is covered in filaments that glint in the sunlight.

It is not a leopard stalking a crocodile, pouncing, rolling, biting and overcoming its prey. But it is just as dramatic.

It is a cliff-face of plants with a thirst for blood.

Share The glistening, sticky droplets are what gives these plants the common name 'sun dews'.

Murderous plants

When Greg Bourke finished school, he went off to become an electrician.

He spent years working that trade, rising up the ranks through telecommunications and travelling much of the continent. But plants were always his thing.

Even when he was working on installations at remote sites, he would find time to wander the surrounding tracks, closely examining the ground for minuscule herbaceous plants.

Share Greg Bourke is one of a small group of intrepid explorers who study the world's carnivorous plants.

"Bushwalking with my parents at four, five years old near my home in the Sutherland Shire I'd see sundews in the wild, and I used to go back to these little red glistening sundews on the forest floor, every time, and think these things are amazing," Mr Bourke said.

"The bigger, more vicious, carnivorous plants, the pitcher plants of Borneo, the North American pitcher plants, the real killers of the jungle — that really captured my imagination.

"I've grown vegetables and flowers and bonsai — all these other things — but carnivorous plants were just something else."

His love for these killer plants convinced him to hang up his electrician's toolbelt — he is now curator of the Blue Mountains Botanic Gardens at Mt Tomah just west of Sydney.

Share The more the insect prey struggles, the more trapped it becomes.

He is also one of the authors behind an encyclopaedic book series called Drosera of the World, listing the knowledge to date of the broad family of plants commonly called sundews.

"Carnivorous plants cover close to 97 per cent of the continent," Mr Bourke said.

"We've got the most diverse range of carnivorous plants on the planet — close to 240 species."

We have so many sundews in Australia because the fertility of our soil has been leached out over millions of years.

To get around the lack of fertiliser, these plants have developed a survival system: they murder insects and compost their bodies.

Glittering killer

Share These West Australian Drosera purpurescens put on a show with their hot-pink clusters.

Though they vary wildly in shape, Drosera leaves can often look like undersea creatures, with tiny stalks coming off the main surface, protruding into the atmosphere.

These matchstick shapes can be all different colours and lengths, even on the same plant, like meaty tentacles on an anemone.

Share Drosera's sticky tentacles trap insect prey.

The common name "sundew" for Drosera is derived from the effect of sunlight refracting through the glistening droplets of digestive enzymes on the plant's tentacles, Mr Bourke says.

"They have this fantastic sticky substance on them that captures a prey item when it touches the plant," he said.

As the insect struggles and flails to try to free itself, it inadvertently makes contact with other glands and becomes increasingly incapacitated.

On top of that, many sundews can move to embrace their prey in a moist grip of deathly goo.

In fact, their lethal speed can be faster than a cheetah at full gallop.

One Australian species might just be the fastest moving plant in the world.

External Link: Drosera gladuligera catapulting its insect prey to be digested

"Drosera glanduligera, moves so rapidly it's faster than the eye can see. It's a couple of hundredths of a second," Mr Bourke said.

"And an ant or prey will walk on that gland and the gland will actually flick that prey item into the centre of the leaf. There is no escape."

Death by drowning

Share A moth falls victim to Drosera's sticky tendrils.

"The insect will often be overcome by the quantity of mucilage that is smothering it, and it will actually drown," Mr Bourke said.

"Or they become so exhausted from trying to escape that the plant just overwhelms them, and pretty much digests them alive.

"It is a slow and painful death."

The next step is digestion. Using a technique that resembles an arachnid rather than a mammal, the plant exudes enzymes onto the wretched prey, liquefying the insect within its own exoskeleton.

External Link: A timelapse of a hoverfly becoming entrapped in a Drosera

It is this aggressive composting strategy that gives the sundews an advantage over other plants in their environment: they find — no, slaughter or harvest — nutrients to grow in an environment where plants would otherwise fail from malnourishment.

"They're out-competing the opposition," Mr Bourke said.

"They're pioneers. We're seeing, I guess you could call it rapid evolution of these plants.

Share Carnivorous plants are found across more than 90 per cent of the Australian landmass.

"They're constantly moving and changing.

"If there's a disturbed area, the carnivorous plants are often the first ones to move in. Because they can get in, get their nutrients and get a foothold.

"There is a group called ... Indian sundews from central and northern Australia that've done away with the ability to bring nutrients from the soil itself.

"They can't actually feed off the soil and bring that nitrogen that they need up to the plant. They have to feed off animal prey to get that nutrient."

But their uncompromising compost strategy remained secret until 1875.

The plant that frightened Darwin

Share Naturalist Charles Darwin feared backlash to his findings that plants were capturing and digesting insect prey.

It was an astounded Charles Darwin who scientifically confirmed that plants could capture and digest prey, after years drawing them, studying them and becoming immersed in their intricate biology.

He wrote in 1860: "I care more about Drosera than the origin of all the species."

In the same letter, he noted: "I am frightened and astounded at my results ... Is it not curious that a plant should be far more sensitive to a touch than any nerve in the human body!"

Mr Bourke says: "Of course, at the time it was blasphemous to suggest that a plant could've turned the tides and be eating animal prey, but Charles Darwin was fascinated by this plant.

"I think it took quite some time for Charles Darwin to release the information for fear of being locked up for being insane."

Darwin delayed the publication of his thesis on insectivorous plants for another 15 years.

Share Drosera aquatica feeds on insects that hatch in the waters where it grows.

"We still just know so little about these plants," said Mr Bourke, who is one of a small band of intrepid and very dedicated plant biologists and enthusiasts who are slowly discovering more carnivorous plants in Australia and the world.

One of their recent finds is an incredible floating plant that lives in Northern Australia.

"The plants just simply float and they capture their prey on the surface of the water," Mr Bourke said.

"They're getting the first insects that are coming out of that water that are hatching and flying away.

"It looks like a miniature pine tree, this glistening little puff of plant on the water's surface."

And just like Darwin before him, Mr Bourke will take risks for his beloved Drosera.

"I've been known to venture into a few croc-infested swamps. But when you're passionate about these plants, you weigh up the risks and say, 'Well, we'll give it a shot'."

The complex killer

Share Though they eat some insects, sundews rely on others to pollinate their flowers.

Carnivorous plants are not just one-faceted heinous herbs; they actually have complicated relationships with insects that extend well beyond the killer and the quarry.

They rely on insects for sexual reproduction and set flowers to attract would-be pollinators.

Of course, it would be unwise to bite the proboscis that pollinates you, so the flowers often grow on long stalks, well away from the lethal leaves.

Fittingly enough for a carnivorous plant, they also enter into symbiotic relationships with assassin bugs.

"Some species of insects are actually employed by the plant to help with the digestion," Mr Bourke said.

"These guys are able to walk around on the leaf's surface without getting captured," he said, pointing to a bug that weaves through a miniature plantation of glands.

"They feed on the prey of the sundew. It comes across and actually sucks the juices from the prey and then deposits it's droppings directly onto the leaf of the sundews. It's like a little package of fertiliser.

"Pure symbiosis — that's as interesting as the plants themselves."

Share The Linx spider links the sticky leaves and stems of Goodenia grandiflora with a basic web to allow it to sense prey that is trapped by the plant.

As more and more plants are being studied, more and more intricate symbiotic relationships are also being uncovered, including a plant in the family Goodeniaceae, which is predominantly an Australian group.

"Spiders live on the plants and they hide in between the leaves and they wait for insects to be caught by the plant," Mr Bourke said.

Flora fatale, the plants with a thirst for blood With an aggressive mass-murder-then-compost strategy, these tiny plants are the most heinous of herbs. Listen to this episode of Off Track.

The spider unfurls a tension wire between the leaves of the plant, then waits for vibrations of stricken prey.

"The leaves are effectively an extension of the web. The spider doesn't need to produce this big, beautiful orb that most spiders do," he said.

While they do not stalk their victims, sundews grow in places that prey will traverse or be blown through on winds.

They can even employ sneaky tactics, with recently published research indicating that sundews can be kleptoparasitic, stealing the pollinating insects right from adjacent plants' flowers.

Not the ideal neighbour then.

Fatal flora

Share Insects trapped in the sticky goo of a Drosera plant.

Everywhere you look in Australian bushland, a cycle of death, dying and digestion is going on.

Crawling along on hands and knees, Mr Bourke can see things the average human just glances across.

"That's a Utricularia — it has these tiny little bladder-like traps, suction traps that are in the substrate. It's feeding on nematodes and mosquito larvae that are in the soil surface. It sucks them into the traps and then slowly digests them," he said.

Share These sticky secretions are a slimy wonder.

He brushes a finger delicately on a plant.

"You can't feel it digesting you, no. It feels a bit like snot. But beautiful snot.

"You can see on this leaf, maybe a dozen prey items. There's a mosquito, a couple of small flies. And you can see the different stages at which they're digesting those insects."

The leaf looks like it has a collection of dryer lint sneezed along its length.

Share Insects blown on the wind get trapped by the carnivorous Drosera plants

"The remains of a crane fly there. It's like a meditation for me, I just love being out in nature. That's where I'm truly relaxed," he said.

"Every plant has a story to tell. With the sundews, when they're feeding like this, it's almost like every leaf has a story to tell.

"So, if we lose the carnivorous plants, its a bit like the frogs — if we lose the frogs we lose the habitat, and the carnivorous plants are great indicators for habitat health.

"If we lose the carnivorous plants, we'll lose the stories that they tell.

"But life on the edge is tough."

Share "We still just know so little about these plants," but Greg Bourke is working to find out more.