Australia-based researchers have released new findings in the field of plant communication. Research was led by Monica Gagliano, a specialist in plant “bioacoutics” and cognition.
Their goal is the study of the plant “electrome”. The term refers to the sum of the electrical signals that pass between cells of living beings and are a major part of how the different parts of the body communicate with each other.
Much of the communication within and between organisms takes place through chemical signaling: your body’s hormones and pheromones, for example. We know that plants “communicate” this way also.
To test whether plants communicate via the electrome, the researchers chose a novel moment: a solar eclipse. The eclipse was visible from a national park, Paneveggio-Pale di San Martino, located in the Dolomites in north-east Italy.
“Here, we monitored multiple spruce trees to assess their individual and collective bioelectrical responses to a solar eclipse,” the study authors wrote. The researchers wired electrodes around three trees: two about 70 years old, one in sun and one in shade, and another tree about 20 years old. They also wired up the stumps of trees that had fallen in a storm several years before.
They found that the trees’ electrical patterns changed hours in advance of the eclipse. In the authors’ interpretation, “Trees anticipated the eclipse, synchronizing their bioelectrical behaviour hours in advance.”
The two older trees seemed to “know” of the impending eclipse hours before the younger tree. The researcher interpreted this as learning and experience on the part of the older trees.
They also say there were electrical waves passing between the trees. This they interpret as an “organism-like reaction” within the forest itself. Such an interpretation is buttressed by other research that shows “carbon trade” via the intertwined root networks of the forest and symbiotic fungi.
Previously, Monica Gagliano is most famous for an experiment that demonstrated basic learning – “habituation” – in Mimosa pudica, research that was showcased by Michael Pollan. This species is known to curl up its leaves when touched.
Gagliano rigged a system that periodically dropped potted mimosa plants from a small height. The jolt caused them to retract their leaves, but over time they “learned” that the stimulus was not dangerous. If she then shook the plants from side-to-side, they “knew” that this was a novel threat and curled their leaves up again.
Debates about plant “communication” and “intelligence” always hang on how those terms are defined. If we focus on free will and consider intelligence to mean contemplation followed by action – and communication as a way to deliberate, share information or to express future intention – then there may never be proof of such a thing in plants. But if we consider it to mean adaptation, responsiveness and experience, there is abundant evidence of natural intelligence.