Doug Bonderud

Mar 30th 2020

Greenery Gone Wild: Could Carnivorous Plants Consume … People?


Plant-based diets are becoming more popular as both moral and methodological objections to meat intensify, but what if the flora we feast on has finally had enough? Recent data suggests that under the right conditions — such as physical damage or drought — plants emit ultrasonic “screams” between 20 and 100 kilohertz that can be heard up to 4 inches away.

And while angry agriculture such as frustrated foxtails or downright disappointed dandelions don’t pose much threat to humankind, carnivorous plants are another story. Could this greenery gone wild ever decide that a human-based diet was the best way to both get healthy and exact its leafy revenge? Here’s what you need to know about killer carnivorous plants.

What’s for Dinner?

Carnivorous plants are often called insectivorous plants — instead of simply subsisting on sunlight, water and soil, these plants pursue insects to supplement their diet. Some wait passively for bugs to fall into their pitcher-like traps, while others actively seek out their next meal. Consider the Venus flytrap: This well-known creature catcher snaps its “jaws” shut when tiny hairs are brushed twice in quick succession by an unsuspecting insect.

The penchant of these plants for more violent nutrient-nabbing isn’t a question of malice: As noted by the Savannah River Ecology Laboratory, these plants typically develop in wetlands “that have little or no drainage and low levels of essential plant nutrients.” By adding insects to their daily dietary requirements, these plants can survive — and thrive — even in less-than-ideal conditions.

But not all carnivorous plants keep to insect kind: According to a recent paper published by Canadian researchers in the Ecology Society of America (ESA) journal, pitcher plants in Ontario’s Algonquin Provincial Park are now consuming baby salamanders, while other pitcher plants prey on small frogs unfortunate enough to go looking for food or shelter in their cup-shaped leaves. Some overly-ambitious flora have been known to eat rats — although the Atlas Obscura notes this is “akin to a human trying to eat a whole cow.” Not impossible, but incredibly difficult.

This certainly ups the “creep” factor of this greedy greenery — are they slowly moving up the food chain, waiting for their chance to bite back?

The Art of Misdirection

While insectivorous plants differ in their approach to snagging another snack, they all share a common approach: misdirection.

The tropical pitcher plant Nepenthes lowii smells sweet to attract bugs, but its slippery surface causes them to lose their footing and fall inside, trapping them for digestion. Other pitcher plants accumulate water to make a tempting pit-stop for small fliers — once inside the waxy surface of species like Nepenthes alata make it impossible for bugs to climb out, even as enzymes steal their precious nutrients.

The South African king sundew (Drosera regia) displays tiny translucent globules that look like water to lure in unsuspecting spiders. Instead, unlucky arachnids encounter thick mucilage globules that become ever more sticky as the spider struggles; when it finally gives up, a long tentacle transports it to the leaf’s center where the eight-legged lunch is turned into a nutrient soup thanks to burning acids and enzymes. Plants like the Cobra Lily, meanwhile, use translucent leaf windows to trick flying insects when they enter the snake-like shape — bugs think they’re flying out when they’re actually flying toward their doom.

It’s another strike for carnivorous plants: Lying is part of the game when they’re competing for survival. Could we get fooled?

Purple People Eaters

Plants do pose a threat to humans — but it’s not because we’re their preferred dietary staple. As noted by Gizmodo, our biggest problems come from poisonous plants; humans eating berries or leaves that contain chemicals like cardiac glycosides that can cause (you guessed it) cardiac arrest or tiny spears of calcium oxalate that cause oral irritation, drooling, swelling and potentially asphyxiation if airways become blocked. Any plant attempting to eat people would find itself overmatched; even small children are too big for plants to digest, and their leaves simply aren’t strong enough to constrain human beings. Still, there’s an interesting thought experiment here: Under what conditions could we find ourselves at the business end of hungry herbs?

The nutrient-poor nature of most carnivorous plant habitats give us our first clue. If ecological damage accelerates on Earth — or if another global war erupts — existing farmland could be virtually wiped out, paving the way for meat-eating plants. And while sweet-smelling flowers might not catch our attention in a resource-scarce world, we’d certainly be tempted by the prospect of clean, abundant water. A host of Drosera regia could pose a tempting target for thirsty humans; if we lost our footing and fell, weakened from hunger and dehydration, into a field of ferocious flora, it could kick off a new craze among the plant carnivores: the people diet.

Bottom line? Carnivorous plants pose no immediate or pending threat to humans, despite our regular consumption of their soil-sucking brethren. Still, extreme circumstances breed extreme outcomes — if you ever find yourself in a post-apocalyptic nutrient-poor bog and spot a shimmering sea of crystal-clear water, you might just be a meal in the making.