Have You Ever Heard of “Plant Intelligence”?
Plant intelligence refers to “any type of intentional and flexible behavior that is beneficial and enables the organism to achieve its goal” (Garzón & Keijzer, 2011). Research has shown that plants have the capacity to communicate, adapt their behavior, and even learn. Some scientists suggest they may possess forms of memory, cognition, or perhaps even consciousness. In fact, studies have found that plants can respond to anesthesia. These findings challenge our conventional understanding of life and cognition. This article explores the science behind plant communication, memory, learning, and goal-directed behavior — and how it may redefine our understanding of intelligence and awareness.
The Controversy Around Plant Intelligence
Before diving in, it’s important to understand the controversy surrounding the concept of plant intelligence. With more than 70 published definitions of intelligence and no consensus within even a single field, scientists vary widely in their views of plants’ capabilities. While our understanding of “intelligence” and “consciousness” continues to evolve, climate journalist Zoë Schlanger emphasizes the importance of remaining open-minded, even amidst uncertainty. She writes:
“Part of me feels like it almost doesn't matter, because what we see plants doing — what we now understand they can do — simply brings them into this realm of alert, active processing beings, which is a huge step from how many of us were raised to view them, which is more like ornaments in our world or this decorative backdrop for our lives.” (Mosley, 2024)
Communication Among Plants
Ever smelled freshly cut grass? If so, you’ve already “heard” a plant speaking. In response to their environment, plants communicate using their roots, stems, leaves, flowers, and fruit. For example, leaves can detect predators or changes in light and sound. Unlike signals in a nervous system, plants send electrical signals through the movement of chemicals.
Roots can detect drought conditions and send signals to the leaves to reduce transpiration and conserve water. Like us, plants can signal distress or warn others of danger. For instance, when attacked by caterpillars, some plants release volatile organic compounds (VOCs) — gaseous chemicals that signal nearby predatory insects to attack the caterpillars.
Understanding these complex forms of communication not only deepens our appreciation of plant life but also has practical implications: improving agricultural systems, enhancing climate adaptation strategies, and challenging how we define intelligence (Yang, 2023).
Learning and Memory in Plants
At a 2014 environmental humanities conference, Australian evolutionary ecologist Monica Gagliano introduced research on the mimosa pudica, or “sensitive plant.” In her experiments, the plants were dropped from a height of at least a foot at regular intervals. Initially, the plants retracted in response. But after repeated drops, they stopped reacting — suggesting they had learned the stimulus posed no real threat.
This behavior implies that plants can learn and remember. Gagliano explains: “Plants may lack brains and neural tissues, but they do possess a sophisticated calcium-based signaling network in their cells, similar to animals’ memory processes” (Gibson, 2016). Gagliano found that plants could form associations between stimuli and outcomes — a hallmark of learning typically seen in animals, as famously demonstrated in Pavlov’s dog experiments.
These findings prompt philosophical questions: What can humans learn from the adaptive capacities of plants? And what does it mean to live among life forms that seem to exhibit cognition — without a brain?
Plant Cognition and Goal-Directed Behavior
Umberto Castiello, a contributor to the Journal of Comparative Psychology, argues that many plant abilities — such as communicating, remembering, recognizing kin, making decisions, and even counting — would be considered “cognitive” if observed in animals (Young, 2020). He proposes that plants be considered “cognitive agents,” a perspective that could help us get to the "roots" of cognition itself.
In one experiment, pea plants allocated root growth based on nutrient stability. When nutrients were limited, they favored the stable source; when abundant, they explored riskier options — suggesting the ability to weigh risk and adjust behavior accordingly.
As chemical ecologist Andre Kessler puts it: “The brain in the plant is the entire plant without the need of central coordination” (Ramanujan, 2024). He likens plant intelligence to a beehive, where each part functions like an individual bee, and the whole plant operates like the hive.
The Anesthesia Experiment: Plants and Consciousness
French scientist Claude Bernard was among the first to suggest that different life forms operate under different physiological principles. He observed that anesthetized plants lost their ability to respond to touch — but regained it once the anesthetic wore off. Remarkably, the anesthetic could inhibit photosynthesis without affecting respiration.
Bernard concluded: “What is alive must sense and can be anesthetized. The rest is dead.” He believed that the widespread sensitivity to anesthetics might be key to understanding the unity of life (Grémiaux et al., 2014).
Rethinking Life, Awareness, and Agency
Understanding plant behavior invites us to reconsider our relationship with nature and how we define intelligence, awareness, and agency. Despite lacking brains or neurons — traits we often associate with intelligence — plants demonstrate learning, decision-making, and intentional behavior.
This raises important questions:
- Can something be “intelligent” without a brain?
- If plants exhibit goal-directed behavior and environmental responsiveness while rooted in place, do they have agency?
- If anesthesia can suppress a plant’s sensory functions in a way similar to how it affects the nervous systems of humans and animals, does this raise ethical concerns about how we interact with plants — such as pruning, harvesting, or conducting experiments?
These questions also invite ethical reflection. How should we coexist with plants if they are more than passive life forms? Many Indigenous worldviews treat plants as relational beings, rather than mechanistic objects — a sharp contrast to the dominant Western perspective.
Final Thoughts
The science of plant intelligence challenges long-held assumptions about cognition and life itself. As we expand our definitions and deepen our awareness, we may find ourselves not just surrounded by greenery — but by an entire world of sentient, adaptive beings we’ve only just begun to understand.