Ravenous Killer Plants: 5 Carnivorous Types

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Carnivorous plants have intrigued mankind extensively since the late 17th century when Charles Darwin wrote of their existence in Insectivorous Plants. These killer plants are known to feast on the flesh of arachnids and insects, and the largest among them can consume birds and even small mammals, enabling them to flourish in nutrient-deficient soil by attracting, trapping, and then killing prey in order to absorb the nutrients needed to grow.

“Sic gorgiamus allos subjectatos nunc.” “We gladly feast on those who would subdue us.” Not just pretty words.

Morticia Addams (The Addams Family (1991))

There are over 500 species of killer plants and approximately three new ones are identified annually. They are commonly grouped according to their trapping mechanisms, which can be active (their traps move) or passive. Here are some paragons of flesh-eating plants by type, many of which can be readily procured by the morbidly curious.

Killer Plants with Snap Traps

Snap trap plants are the first carnivorous type that comes to mind when most people hear the phrase “killer plants.” The 1960 horror comedy stage play, subsequent musical, and 1986 film Little Shop of Horrors propelled the snap trap type into the pop culture spotlight with its larger-than-life caricature of a Venus Fly Trap named Audrey Two, and although there are no known instances of a Venus Fly Trap big enough to consume a human being in reality, there’s no doubt that they would if they could.

Snap traps have the most rapid movement, called thigmonasty, among killer plants. Ever shrouded in mystery, there are theories on how this movement occurs, but no one knows for certain, adding to its allure.

Venus Fly Trap (Dionaea muscipula) is the most popular among snap traps, but there is another aquatic one called the Waterwheel Plant (Aldrovanda vesiculosa) that has many similarities to its terrestrial cousin.

The two plants share very similar traps – leaves divided into two lobes, hinged along the midrib that have multiple trigger hairs within them. Both traps will snap shut when their trigger hairs are contacted twice within a 0.5 to 30 seconds interval. The process takes only a fraction of a second.

The major difference between the Venus Fly Trap and the Waterwheel Plant is their prey. Dionaea muscipula will trap arthropods like aphids, spiders, and the common housefly. Aldrovanda vesiculosa traps small freshwater invertebrates such as water-fleas, tiny shrimp and protozoa.

Additional differences include trap size, root system, and span. The Venus Fly trap has larger traps (~1 inch), is rooted in the ground, and reaches a maximum height of 12 inches. The Waterwheel’s traps are very small (¹⁄₁₆–¹⁄₈ in) and is a rootless floating plant that grows to lengths up to 16 inches.

Flypaper Traps

Carnivorous plants with flypaper traps secrete a sticky glue-like substance called mucilage that renders prey immobile as they digest their flesh. The exemplars of this category are Drosera, Drosophyllum, and Pinguicula, more commonly known as sundews, the dewy pine, and butterworts, respectively.

Sundews have active traps, while dewy pines have passive traps, but are otherwise similar. They both have long, sticky extensions growing from a central rosette. On sundews, they are tentacles that will slowly bend around trapped prey to prevent escape. Dewy pines, on the other hand, have woody branches that do not have a thigmonastic response.

Prey succumbs to exhaustion from trying to break free from the mucilage, or suffocate in the process.

There are more than 100 different species of sundew that can be found on every continent except Antarctica, and only one dewy pine species (Drosophyllum lusitanicum). The dewy pine is native to Portugal, Spain, and Morocco, and is one of the only carnivorous plants that grow in dry soil, as opposed to wet, bog-like conditions.

Owners of plants with flypaper traps that provide them a suitable environment will be pleased with the plants’ ability to capture and digest multiple insects or arachnids at a time. Sundews primarily catch small insects due to their size, but dewy pines will attract and kill large flies, wasps, and hornets.

Butterworts (Pinguicula spp.) also grow from rosettes, but don’t have mucilage glands as pronounced as the sundews and dewy pine. They can be seen upon close inspection and are spread across leaves instead of stalks or tentacles. Some butterworts have a thigmonastic response like the sundews in which their leaves fold slightly to maximize contact with their prey. The more their prey struggles, the more mucilage gets excreted by this killer plant, typically resulting in suffocating their victims.

There are approximately 80 species of Pinguicula and all of them flower. They can only catch small insects but will also digest pollen that lands on their leaves.

Pitfall Traps and Lobster-pot Traps

There are many carnivorous species that rely on pitfall traps to capture their prey, and lobster-pot traps have some similar mechanics. Their victims venture into these traps, and either drown in the plant’s digestive fluids or die from exhaustion during their futile attempts to escape.

Darlingtonia and Nepenthes are two popular examples of the pitfall trap.

The dramatic Cobra Lily (Darlingtonia californica) resembles a snake prepared to strike. It has a bubble-shaped crown with a small opening underneath that is frequently accessed by crawling insects like ants. They make their way into the opening and eventually fall into the long shaft of the plant where they are trapped and digested.

Nepenthes are often referred to as “monkey cups” or pitcher plants and have long stems with open pitcher-shaped containers attached at the ends. The different species widely vary in size, but the trap is basically the same – insects are lured in by the plants’ aromas and fall into the sticky digestive fluid within. The largest among the Nepenthes, Nepenthes rajah, will also trap rats, birds and reptiles.

Genlisea, a semi-aquatic variety commonly known as the Corkscrew Plant, does not have a pitcher. Instead, this killer plant has long corkscrew-shaped tubes that grow underground, preying on protozoa and the like.

In much the same way the Cobra Lily works, victims enter one of many bulb-shaped openings which have corridors that split into the long, winding tubes of the Corkscrew Plant. The prey cannot find their way out and perish in this “lobster-pot trap,” where they are digested and absorbed, much like roots extract nutrients from soil.

Bladder Traps

The final example of carnivory in plants are the bladderworts (Utricularia spp.), named after the traps that they utilize for nourishment.

Most bladderworts are terrestrial and grow in wet soil conditions, while others are fully aquatic. Both types leverage their watery surroundings to trap small protozoan prey.

Their bladder-shaped traps are negatively pressurized like a vacuum on the inside, with a hinged door sealing off the outer pressure. When swimming protozoa (or water fleas for the larger aquatic types) make contact with tiny hair on the trap door, it triggers the trap, the door opens for approximately 0.01 seconds, and the murderee is sucked inside to be digested.

There are some types of flesh-eating plants that possess combinations of these five carnivorous types of traps, which we’ll save for another time and place. “For whoso hath too much of any good, Of that same good he shall be soon bereft.” (John Lydgate – The Fall of Princes)