Shocking Discovery About the Evolutionary Path of Transforming Plants into Carnivorous Plants

At the end of the 19th century, fictional stories about “killer” plants began to spark conversations among people in many places. In these tales, a type of plant is described with long, meter-long tendrils resembling the tentacles of a giant octopus, wide buds divided into smaller branches like the jagged jaws of a predator, which then use these features to engulf unwary travelers in distant lands.

Never before in history had people believed and felt fear at the thought that : “Plants can also stalk and kill living creatures“. So, what lies hidden and waits for us beyond the primeval forests or in places where humans have never set foot?

For scientists, they are also facing a significant moment as they begin to uncover the first evidence for one of the greatest puzzles in botany: “How did certain plant species evolve to become carnivorous predators?”

Carnivorous Plants: What Are They?

When we talk about carnivorous plants, we might immediately picture a trap made of vines and a “pitcher” structure that helps the plant capture unfortunate creatures that wander inside.

However, in reality, around 800 species of carnivorous plants are known to humans. Some species, like the pitcher plant and many types of sundews, passively capture prey, waiting for unsuspecting insects—usually flies, bees, or small bugs—to come and fall into the trap.

On the other hand, there are also more “active” plant species, such as Drosera, belonging to the family Droseraceae, which can actively push the prey into the center of the “trap,” where they become stuck and are digested to death, or some species with tendrils that move quickly enough to “bind the feet” of their victims.

Most sophisticated of all is the Venus flytrap (Dionaea muscipula), which has highly sensitive trigger hairs and a trap lid that can gauge the size of its prey and respond accordingly.

Despite the vast differences in shape, form, and methods of killing prey, all these carnivorous plants share a common feature: their “traps” are made from leaves, or parts of leaves that have been modified to become distinct from regular plants.

Scientists have discovered that when insects struggle and generate electrical signals inside the trap, carnivorous plants begin to produce a chemical compound called jasmonate, which serves as a signal to “seal” the edges of the trap. They then start filling it with digestive enzymes.

The list of enzymes includes chitinase, which breaks down chitin (the hard outer shell of most insects); protease, which breaks down proteins; and purple phosphatase, which allows the plant to extract usable phosphorus from the unprocessed remains of its victims. These enzymes operate similarly to many types of chemical weapons with plant components, used to combat harmful bacteria, fungi, and herbivorous insects.

As the insect remains decompose, the trap absorbs its enzyme output and begins to produce nutrient transport substances again under the control of jasmonate concentration.

Tanya Renner, an evolutionary biologist at Penn State University, asserts: “This means that these plant varieties not only extract nutrients from their roots but also through another pathway, primarily through their leaves.”

From ancient times to the era of Charles Darwin—the father of evolution—most people rejected the idea that plants could “eat” animals. This notion clearly contradicted the natural order, where animals are mobile while plants are not. If they cannot move, how could they “hunt” and become predators?

Darwin spent 16 years diligently working in laboratories to prove the opposite. He pointed out that the leaves of certain plant species have been modified into special structures that not only trap insects and other small creatures but can also digest and absorb the nutrients released from their remains.

As a result, in 1875, Darwin published the book “Insectivorous Plants”, detailing all he had discovered about these plants. In 1880, he released another book titled “The Power of Movement in Plants.”

At that time, the realization that plants could move, or even kill other animals, inspired not only horror films with similar themes but also motivated many generations of biologists to delve deeper into these plants with perplexing habits.

Thanks to Darwin’s theories, botanists, ecologists, entomologists, physiologists, and molecular biologists gained a comprehensive understanding of all aspects of plants capable of “drowning” their prey in liquid-filled containers, immobilizing them with sticky trap-like leaves, or imprisoning them in snap traps, and then “digesting” the remains in a stomach-like modified structure.

But how could plants—still considered “unfeeling and insensate” in our eyes—evolve in such a sophisticated way, even resembling the methods that animals once used to eat them on this Green Planet?

One hypothesis suggests that these plants have acquired genes from animals that accidentally became their “prey.” In other words, they absorbed predatory genes to become a distinct species, a hybrid between plants and animals.

However, biophysicist Rainer Hedrich from the University of Würzburg in Germany, who explored the origins of carnivorous plants in the “Journal of Plant Biology 2021”, stated that there is no evidence that carnivorous plants acquired this “predatory” habit by commandeering genes from their animal victims. He acknowledged this, even though genes can sometimes be transferred from one organism to another.

Instead, these plants have actually replaced existing genes with more advanced functions.

According to Victor Albert, a plant geneticist at the University of Buffalo, this evolution has been incredibly “stealthy and flexible.” “In the evolutionary process, reusing something is simpler than creating something new,” Albert shared.

The Path to Becoming a Predator

Another hypothesis that most scientists agree on is convergent evolution. Convergent evolution is an important driver of evolutionary innovation and often begins with random copying of genes during cell division.

While most gene copies serve no original purpose and will eventually be eliminated, there are instances when backup genes acquire beneficial mutations. This paves the way for changes in the function of the species.

“Gene copying is always happening and sometimes it is highly adaptive,” Albert said. “This seems to be how carnivorous plants developed their predatory abilities—at least for the genes that have been tested so far.”

In 2017, evolutionary biologist Kenji Fukushima, along with Albert and a team of international researchers, sequenced the genome of a carnivorous plant native to Australia called Cephalotus follicularis. Like many other carnivorous plants, Cephalotus traps prey in a structure resembling small “jars.”

A significant surprise occurred when they investigated the origins of the digestive enzymes in Cephalotus and three other unrelated species, including Nepenthes alata (an Asian pitcher plant), Sarracenia purpurea (North American pitcher plant), and Drosera adelae from the Sundew family.

It turned out that all four species had rearranged the same type of ancient enzyme, matching the enzymes previously identified in the Venus flytrap.

Victor Albert, a co-author of the study, stated that this is a classic case of convergent evolution. According to him, this method indicates that there are only a few specific and highly limited pathways for ordinary plants to evolve into a carnivorous species.

As the enzymes assumed new roles (related to carnivory), they continued to evolve, swapping some amino acids for others to enhance performance, which could increase reaction speed or raise the concentration of protein-degrading chemicals contained within them.

To date, scientists are very close to answering one of the greatest mysteries in plant evolutionary theory. However, a new question arises: how many other plant species have or will find their own evolutionary paths? If Darwin were here today, he would undoubtedly roll up his sleeves to tackle his unfinished work.