Plants aren't just passive; they sense, learn, and decide
Traditionally, plant behavior was assumed to be entirely determined by genes or environment, and plants were considered noncognitive [1]. However, empirical research now shows that plants have evolved refined sensory abilities to constantly monitor their surroundings [2]. They can perceive, learn, and make decisions—behaviors that were once thought to be exclusive to animals [3][4].
For example, plants can integrate information from their environment and adjust their growth or physiology accordingly. This challenges the view that plants are simple automatons. Instead, their behavior appears flexible and context-sensitive, which is a hallmark of cognitive processes in a broad sense [3][5].
Cognition may not require a brain
One reason plants are often excluded from discussions of cognition is the assumption that cognition requires a nervous system. But some researchers argue that cognition can be understood as a substrate-neutral regulatory process—a way of processing information and regulating behavior that doesn't depend on neurons [5]. In this view, cognition is present even in non-neural organisms, as an integration of perception, memory, and adaptive problem-solving [5].
This framework treats plant cognition not as an anomaly but as a consistent expression of biological agency, shaped by evolutionary constraints [5]. Plants may use electrical and chemical signaling to achieve sophisticated behavior, and research on plant neurobiology is beginning to uncover the biological bases for these capabilities [1].
Evolutionary trade-offs shape plant cognition
Even if plants have cognitive abilities, they may differ from animal cognition because of evolutionary trade-offs. For instance, plants show evidence of kin recognition and may adjust their behavior based on relatedness, indicating a clear evolutionary trade-off in plant kin interactions [4]. This suggests that plant cognition is tailored to their sessile lifestyle and ecological challenges.
The cognitive mechanisms in plants are still being identified, but the evidence is enticing and suggests that plants possess cognitive competences that are adapted to their own survival needs [4]. Rather than asking why cognition hasn't evolved in plants, researchers are now exploring how plant cognition evolved and what form it takes.
Sources used in this answer
Consciousness and cognition in plants
The paper reviews empirical evidence and theoretical perspectives on plant cognition and consciousness, arguing that sophisticated cognitive capabilities traditionally assumed to be exclusive to animals are exhibited by plants, and inviting debate on whether plants might be conscious.
Extended cognition in plants: is it possible?
The paper investigates the possibility of extended cognition in plants, noting that plants have evolved refined sensory abilities to constantly perceive and monitor their surroundings.
Intelligence, cognition, and language of green plants
The paper explores intelligence and cognition in plants by defining these concepts and examining plant behaviors such as decision-making, environmental awareness, and communication.
In a green frame of mind: perspectives on the behavioural ecology and cognitive nature of plants
The paper examines the cognitive nature of plants, providing evidence that plants can perceive, learn, and make decisions, and suggesting an evolutionary trade-off in plant kin interactions.
Biological agency as the context for plant cognition
The paper introduces the Agency–Process–Scale framework, which treats cognition as a substrate-neutral regulatory process present in all living systems, including plants, and reframes plant cognition as a consistent expression of biological agency.