What is plant intelligence

Mimosa! You might think this plant is sensitive or frightening - but not clever. But that is exactly what the Italian botanist Stefano Mancuso means. He considers the touch-sensitive plants to be extremely docile. "Mimosas do not fold their leaves when they are touched, they are able to differentiate between dangerous and harmless stimuli," explains Mancuso. "And they can learn from experience."

To demonstrate this, the botanist repeatedly dropped potted mimosa from a small height on a soft surface. Initially, the plants folded their leaves after each impact, but after the sixth fall at the latest, they no longer showed any reaction. Apparently they had learned that the shock does not harm them. Even a month later, the plants could still remember what they had learned and were unaffected by further falls.

Experience, learn, remember - Stefano Mancuso considers plants to be intelligent beings. That is why his institute at the University of Florence is also called the International Laboratory of Plant Neurobiology. The name of the institute is a provocation for many research colleagues, after all, plants have no nerve cells, not to mention an organ that processes information centrally. Nevertheless, Mancuso sticks: "Mimosas clearly show memory, even without a brain."

Is it free will when the lima bean emits a cry for help?

Since plants cannot escape and always have to expect to be nibbled on, they have a fundamentally different physique than most animals. They do not have specialized organs such as the lungs, heart, stomach or even a brain, but are built up modularly.

There are only a few different plant parts such as leaves, roots, twigs that repeat themselves and all perform similar tasks - therefore the loss of individual parts is tolerable for the plant. Despite these fundamental differences, Mancuso believes that plants have capabilities that are in no way inferior to those of animals.

In his recently published book "The Intelligence of Plants" (Kunstmann Verlag) the researcher gives numerous examples of plant behavior that astonish the reader. If the lima bean is attacked by voracious mites, it attracts an even more voracious mite with a scented cocktail, which eats the parasite off the stalk. And the roots of the American sea mustard can even recognize whether they are growing between foreign or related plants and accordingly behave more or less in solidarity.

While they grow unrestricted with unfamiliar neighbors, they leave space for the roots of related plants and thus access to nutrients. Clever? At least the supposed dull green stuff actually seems to be less helpless and passive than expected. Nevertheless, skepticism remains after reading it. Aren't most of the cases simply a matter of stimulus-reaction chains? Is that intelligence already?

"When I speak of intelligence, I mean the ability to solve problems," says Mancuso. "And plants solve problems by making decisions, just like animals and humans." In the event of mite infestation, the Lima bean makes the decision to send out a cry for help via scent molecules. "If you like, you say free will to it."