Plant cognition

Do plants taste, see, hear, think, feel pain, and enjoy kinship – do they, like us, hope and strive? Isn’t this just anthropomorphism? Evolution, after all, is a mechanical roll of the dice. If we attribute human purpose or agency to plants, are we simply projecting our own experience onto them?

This skepticism has deep roots, but recent science tells a different story. As Baluška et al. (2020) observe, “Many sophisticated cognitive capabilities traditionally assumed to be exclusive to animals are exhibited by plants too”.

The challenge, then, is not whether plants think like us, but how to understand their intelligence on its own terms. As Trewavas (2014) notes, “Intelligence is the ability to adapt behavior to circumstances, within the lifetime of the organism.” Humans seem special because they do so through reason and belief, but plants are equally special because they adapt through their own structures, processes, and behaviors.

Do Plants Think? An APS Perspective

At first glance, the question Do plants think? sounds almost absurd. Thinking is something we normally reserve for humans and perhaps animals with brains and nervous systems. Plants, by contrast, are rooted, silent, and seemingly passive. They grow, reproduce, and harness sunlight—but surely they don’t think, do they?

And yet, this question has begun to attract serious scientific attention. In recent decades, biologists and philosophers alike have asked whether plants, despite lacking neurons, might display forms of cognition: the ability to sense, process, and respond to their environments in flexible, adaptive ways. The debate is not just about semantics. It challenges how we define life, how we interpret intelligence, and how we place ourselves within the living world.

The APS (Agency–Process–Scale) framework offers a way to approach this question that avoids both uncritical anthropomorphism (“plants have minds just like ours”) and reductionist dismissal (“plants are mere automatons”). Instead, APS starts from a deeper principle: life is best understood through agency—the capacity of living systems to initiate and sustain their own organization, to regulate themselves in pursuit of continued viability, and to adapt across scales of time and space. If we ask whether plants think, we are really asking how plant agency expresses itself, and whether cognition is part of that expression.

Rethinking Cognition Beyond Brains

For centuries, cognition was equated with the mind, and the mind was equated with the brain. This legacy still shapes our intuitions. But research has increasingly revealed cognitive phenomena in places where brains are absent. Single-celled organisms like slime molds can solve mazes, bacteria can perform quorum sensing, and immune systems can “remember” past encounters. These capacities blur the boundaries between physiology, adaptation, and cognition.

Plants extend this challenge further. They detect light, gravity, touch, temperature, water gradients, and chemical signals from other organisms. They can distinguish self from non-self, mount immune-like responses, and even communicate with one another through airborne volatiles and root exudates. Some plants “learn” by altering their responses when conditions change—an ability strikingly similar to habituation in animals.

To call these phenomena thinking may sound metaphorical, but they reveal a genuine cognitive dimension: plants gather information, process it, and adjust their behavior in ways that promote survival and flourishing. APS helps clarify why this should count as cognition without insisting that it is the same as human thought.

Agency as the Basis of Cognition

From an APS perspective, cognition is not a mysterious mental faculty but the informational dimension of agency. Every living system must not only carry out metabolic processes but also track and regulate the conditions under which those processes remain viable. To persist, organisms must sense changes in their environments, interpret those changes in relation to their needs, and act accordingly.

Plants exemplify this vividly. Stomatal pores open and close to regulate gas exchange while balancing water loss against photosynthesis. Roots grow toward nutrient-rich zones and away from toxins. Leaves adjust orientation to optimize light capture. These are not mere reflexes; they are context-sensitive adjustments that integrate multiple signals across scales—from the molecular to the whole organism to the ecosystem.

In this way, plant cognition can be seen as the decision-making layer of agency—not conscious in the human sense, but nevertheless purposive in a biological sense. Plants do not passively endure their environments. They actively negotiate them.

Thinking Without Brains

The phrase “Do plants think?” remains provocative precisely because it forces us to confront the limits of our language. If thinking requires neurons, then plants cannot think. But if thinking is broadened to mean the capacity to evaluate information and act adaptively on it, then plants clearly do.

APS resolves this tension by shifting the focus from traits to processes. Instead of asking whether plants meet a checklist of features (brains, language, abstract reasoning), we ask how they enact the processes of agency across scales. From this perspective, cognition is not something added on top of life—it is an intrinsic aspect of what it means to be alive. Plants show us this in a form that is distributed, embodied, and non-neural.

This reorientation has two benefits. First, it prevents anthropocentric bias. Plants are not “failed animals” or “lesser minds.” They express cognition in ways suited to their evolutionary strategies. Second, it deepens our understanding of cognition itself. By studying cognition without brains, we begin to see its fundamental logic: not consciousness or self-reflection, but the continuous work of maintaining viability in a complex, changing world.

Why the Question Matters

Asking whether plants think is not just a curiosity. It reshapes how we frame biology as a whole. If cognition is grounded in agency, then it is not a rare property but a universal feature of living systems, expressed differently at different scales. This recognition invites a shift in scientific explanation. Instead of separating “higher” from “lower” organisms, or mind from matter, we can explore life as a continuum of agential, processual, and cognitive activity.

For human culture, this shift carries profound implications. It challenges us to reconsider our place in the biosphere. If plants, too, participate in cognition, then intelligence is not the crown jewel of one lineage but a shared inheritance of life. Our interactions with plants—whether in agriculture, conservation, or daily living—take on new depth when we see them as partners in a cognitive world.

Toward an APS Account of Plant Cognition

So, do plants think? The APS answer is both yes and no. No, plants do not think in the human sense of conscious deliberation. But yes, plants do enact cognition as the informational dimension of their agency—sensing, interpreting, and acting to sustain themselves across scales.

By grounding plant cognition in agency, process, and scale, APS provides a framework that is both scientifically rigorous and philosophically defensible. It avoids the pitfalls of anthropomorphism while also refusing to reduce plants to mere machines. In doing so, it opens a space for reimagining not only what plants are, but what life itself entails.

Historical Background

The question of whether plants can sense, learn, remember, or make decisions has intrigued thinkers for millennia. In antiquity, Aristotle speculated about the sensitivities of plants, while later naturalists such as Darwin carefully documented their movements and responsiveness. These early observations hinted that plants might engage with their environments in ways more active than mere growth and reproduction.

By the 20th century, however, such ideas fell out of favor. As biology turned toward mechanistic explanations and gene-centered models, plant behavior was increasingly reduced to chemistry and physiology. Lacking brains or nervous systems, plants were excluded from serious discussions of cognition, which was assumed to belong exclusively to animals.

In recent decades, this view has been challenged. Advances in plant physiology, molecular biology, and ecology have shown that plants detect and integrate a wide range of environmental cues. They adjust to changing conditions, exhibit forms of plasticity that resemble memory, and coordinate their internal processes through distributed biochemical networks. These findings revived old questions in a new key: are such capacities merely metaphorical “as if” behaviors, or do they represent genuine cognition?

This debate has gained momentum within a broader reorientation of biology—from narrowly reductionist approaches to more dynamic, systems-oriented perspectives. In this shifting landscape, plant cognition is no longer a marginal speculation but part of a larger effort to rethink what cognition itself means across the living world.

1. The Case Against Plant Cognition

While plants display impressive environmental sensitivity and coordination, many researchers argue that this does not justify attributing mentalistic states—such as consciousness, sentience, or subjective cognition—to them. Traditional neuroscience defines cognition in terms of recursive, representational dynamics emerging from centralized architectures like brains and nervous systems. By these standards, plants lack the structural prerequisites for consciousness.

The term “plant neurobiology,” though evocative, often stretches analogies between animal neural systems and plant signaling mechanisms. Critics caution that such language, unless clearly metaphorical, risks misleading interpretation by implying structural homology where none exists. Rather than demonstrating subjective experience, plant responses are typically framed in terms of evolved, distributed physiological functions.

Philosophically, cognition entails a subject of experience—an entity capable of intention, evaluation, and choice. Plants, despite their remarkable adaptability, do not meet this criterion. Their behaviors are non-representational and emerge from biochemical and morphological coordination aligned with survival and reproduction. This form of responsiveness, while intelligent in its own right, is better described as mindless agency rather than conscious cognition.

In semantic terms, expressions like “plant memory” or “plant intelligence” may obscure more than they clarify if left unqualified. For scientific precision, such descriptors should be framed functionally rather than experientially. Functional adaptation can occur without intention, and intelligence need not imply awareness.

Thus, from a neurocentric and representational standpoint, plants do not qualify as cognitive in the psychological sense. Recognizing this distinction does not diminish the complexity of plant behavior—it clarifies the nature of their responsiveness. By resisting the conflation of biological function with mental states, we sharpen our understanding of the unique forms of non-neural agency that govern plant life.

Consciousness and Sentience

The question of whether plants possess consciousness or sentience remains highly controversial and is largely rejected within mainstream science. Most researchers argue that the absence of a central nervous system, subjective awareness, or pain perception precludes any meaningful sense of phenomenal experience in plants. Nevertheless, some theorists have speculated about forms of non-neural sentience or “basal cognition,” particularly in relation to slow, embodied responsiveness and self-regulation. These views often align with enactivist or panpsychist philosophies but lack empirical support. The prevailing consensus is that while plants may be cognitive in a functional or behavioral sense, they do not exhibit subjective consciousness.

Representation, Reactivity & Methodological Caution

A central objection to plant cognition arises from the claim that plant behavior, while complex, is fundamentally reactive rather than representational or goal-directed. Critics argue that responses to stimuli can be fully explained by mechanistic, stimulus-response loops without invoking cognitive processes. Furthermore, skeptics warn against anthropomorphism and the rebranding of adaptive physiology as “cognition” without clear criteria. They emphasize the lack of evidence for internal representations, memory encoding mechanisms, or decision-making under uncertainty. Methodologically, the field faces challenges in separating true learning from priming or habituation and often lacks the repeatability and rigor found in animal cognition studies. These critiques call for caution and conceptual precision when attributing cognition to plants.

2. Biological Agency Without Brains

The notion that cognition requires a brain has long shaped biological thinking. Yet the foundational principle of life—biological agency—emerged billions of years before neural systems evolved. This agency refers to the intrinsic capacity of living organisms to act in ways that promote survival, adaptation, and reproduction. It is not a metaphor or mental projection, but an empirically grounded, evolutionarily conserved feature of life.

At its core, biological agency encompasses two concepts. The biological axiom defines life through universal properties: the abilities to maintain integrity, persist over time, and evolve. The biological imperative expresses how these properties manifest functionally—as goal-directed behaviors driven by the need to thrive in dynamic environments. Together, they clarify that agency is not limited to animals or minds. Even photosynthetic microorganisms acted agentially long before consciousness or cognition appeared.

Plants, like all organisms, enact this imperative through species-specific strategies. While structurally distinct from animals, their behaviors—root foraging, phototropism, systemic signaling—serve the same evolutionary ends. Function, not form, governs selection: what matters is how effectively traits serve the organism’s imperatives.

Describing agency across species presents semantic challenges. Human agency is often cast in psychological language: desire intention, planning. But these terms do not translate directly to non-human organisms. Avoiding them risks stripping life of its purposiveness; embracing them risks anthropomorphism. The current solution is functional metaphor: using human-derived language heuristically, without implying shared consciousness or cognition.

Importantly, non-human agency is not metaphorical—it is real, observable, and naturalistic. Human agency builds upon this deeper substrate of mind-independent purposiveness. It doesn’t replace it. Yet science often treats agency as requiring mental states, discounting the evolutionary logic embedded in all life forms.

Clarifying the distinction between agency and mind is essential. Plants lack minds but not agency. Their behaviors are adaptive, coordinated, and evolutionarily significant—even if they lack subjective experience. Cognition without consciousness is not a contradiction. It is a recognition that goal-directed responsiveness is fundamental to biology, not an exclusive trait of minds.

By naturalizing agency through causal, systemic explanations, we can study plant behavior without appealing to mysticism or metaphor. This reframing doesn’t inflate cognitive claims—it grounds them in biology. Plants act not because they think, but because they are alive.

Being mentalistic

To avoid confusion and ambiguity, the APS (Agency–Process–Scale) framework must explicitly distinguish between metaphorical and functional language when discussing cognition in non-animal systems like plants. While APS affirms that cognition, purpose, and agency are not exclusive to animals with nervous systems, it also cautions against uncritical extensions of human mental terms such as reasoning, memory, or decision-making without clarifying their biological context and meaning. For instance, it would be misleading under APS to claim that plants “reason” in any propositional or inferential sense; rather, plants exhibit forms of adaptive behavior and context-sensitive modulation that are functionally analogous to reasoning but grounded in physiological processes rather than abstract logic or symbolic representation. Similarly, terms like plant neurobiology can be useful for drawing attention to plant electrophysiology and signaling networks (e.g., action potentials, calcium waves), but APS avoids implying that these are equivalent to animal nervous systems or involve neural computation.

APS strengthens its conceptual clarity by focusing on functional equivalence rather than structural similarity. It recognizes that the cognitive-like capacities observed in plants—such as environmental assessment, signal integration, anticipatory behavior, and self-regulation—emerge from the coordinated activity of multiscale processes that sustain life. These capacities constitute a form of minimal or basal cognition, not because plants think or feel, but because they act in ways that are meaningfully agentive and goal-directed within their ecological and evolutionary contexts. To reinforce this distinction, the APS framework benefits from consistently grounding such terms in biological mechanisms, not metaphors, and emphasizing that human mental faculties are highly elaborated expressions of these foundational properties, not separate in kind but continuous in evolutionary and functional terms.

3. The APS Framework Explained

The APS framework (Spencer, 2025) —Agency, Process, Scale—provides a scientifically grounded alternative to both mechanistic reductionism and mentalistic overreach in biology. It reframes core concepts such as function, cognition, and purpose without relying on either genetic determinism or neural consciousness.

Agency refers to the intrinsic, evolved capacity of living systems to initiate and regulate actions in accordance with the biological imperative—the drive to maintain integrity, adapt to change, and persist through time. This agency is not conscious or intentional; it is grounded in the functional organization of the system. Plants, like all organisms, sense, respond, and coordinate internal processes to meet environmental challenges.

Process highlights that living systems are not static things but dynamic, interactive activities. Organisms are composed of ongoing, recursive processes—metabolism, signaling, growth, repair. Cognition-like properties—such as environmental assessment, memory, or signaling—can emerge from these continuous, self-organizing dynamics, without requiring a nervous system (Maturana & Varela, 1980).

Scale insists that life must be understood across multiple levels of organization—from molecules to organs, organisms, and ecosystems. Agency and cognition are distributed phenomena, not localized in a brain or gene. In plants, coordination and responsiveness emerge from interactions across these nested scales (Wolkenhauer & Hofmeyr, 2020).

APS matters because traditional biology often marginalizes non-neural intelligence by equating cognition with consciousness. The APS framework rejects this conflation. It provides a rigorous, naturalized account of purpose and adaptiveness, grounded in the real capacities of living systems—not imagined analogies with animal minds.
Through APS, plant cognition becomes scientifically legitimate—not as metaphor or anthropocentric projection, but as a real expression of living organization shaped by evolutionary and ecological pressures. Plants are not passive. They do not need a brain to behave intelligently. They are agents, processes, and multiscale systems shaped by the imperative to live.

4. Rethinking Cognition in Plants

Cognition has long been equated with mental states—thought, awareness, and self-reflection. But from an evolutionary standpoint, cognition is not defined by consciousness. It is the capacity to sense, process, and respond to information in ways that promote adaptive behavior. By this definition, cognition is neither rare nor exclusively human: it permeates life.

Plants demonstrate cognitive capacities through adaptive, self-regulating behavior across space and time. They navigate light gradients, differentiate between kin and competitors, and optimize resource use. Their actions are shaped by cues from soil nutrients, wind patterns, and microbial networks—not by brains, but by intricate physiological systems.

This redefinition challenges traditional boundaries. Cognition without neurons was once considered oxymoronic; now it is biologically plausible. Sensory integration, memory, and decision-like behavior have all been documented in plants. These functions do not require subjective experience. They emerge from feedback loops and distributed signaling networks that regulate growth, defense, and reproduction.

Terminology remains a challenge. Words like memory, learning, and decision-making are borrowed from psychology. When applied to plants, they serve as functional metaphors: not implying consciousness, but describing causal, adaptive mechanisms. Critics argue this language anthropomorphizes nature. Yet stripping life of cognition because it lacks a mind obscures its complexity.

Reframing cognition as an evolutionary strategy, rather than a mental event, dissolves this tension. Cognition is not binary—having or lacking—it is graded and context-dependent. Human cognition is embedded in conscious experience; plant cognition is embedded in material responsiveness. Both are real, just expressed differently.

To naturalize plant cognition, researchers are mapping biological substrates—hormonal gradients, electrical signaling, gene-regulation networks—that underlie intelligent behavior. These systems do not simulate brains; they represent alternative architectures for solving problems evolutionarily.

Rethinking cognition in this way deepens our understanding of life’s diversity. It expands biology’s explanatory toolkit and invites broader questions: What is cognition for? How did it evolve? How do living systems—regardless of structure—coordinate themselves in a purposive way?

The answer, increasingly, is clear: cognition is a biological feature, not a mental construct. It is how life organizes itself to persist.

5. Cognition Without a Nervous System

The idea that cognition requires a brain—or at least a nervous system—has long shaped how intelligence is understood, both scientifically and culturally. Intelligence, in this frame, is measured against human capacities for memory, learning, reasoning, or abstract thought. But such anthropocentric models systematically exclude non-neural organisms. Plants are not cognitively inert because they fail to meet neural criteria; rather, the criteria themselves are misplaced.

In a biological context, cognition refers not to language or logic, but to a system’s capacity to acquire, process, and respond to information in a goal-directed manner (Lyon, 2006; Calvo & Keijzer, 2011). On this view, cognition is not something organisms have—it is something they do. It is not localized in a brain, but emerges from the organization of living processes across scales (Di Paolo et al., 2017).

Plants, accordingly, display many hallmarks of cognition: they perceive light gradients, sense gravity and moisture, and respond to tactile cues. They integrate internal and external signals to modulate development, allocate resources, and coordinate growth. These behaviors are anticipatory, flexible, and context-sensitive—qualities typically associated with learning or decision-making (Trewavas, 2014; Calvo, Sahi, & Trewavas, 2020).

Crucially, these capacities are not metaphorical projections. Plant cognition is not a fanciful analogy, but a functional description. The mechanisms may differ from neural systems—relying on membrane potentials, hormonal signaling, and bioelectric fields—but the outcomes are strikingly similar: adaptive behavior driven by internal regulation and environmental information. This is not rudimentary intelligence—it is a different architecture of cognition (Baluška & Mancuso, 2009; Segundo-Ortin & Calvo, 2021).

Recognizing cognition in plants demands a shift in explanatory stance. Rather than asking whether plants have minds like ours, we ask how they solve problems, maintain themselves, and respond meaningfully to their world. This is not to anthropomorphize plants, but to biologize cognition. If cognition is understood as the functional coordination of behavior in service of survival, then plants are unequivocally cognitive beings.

This reframing has important implications. It reveals that cognition is not a late evolutionary innovation, but a foundational property of life. Nervous systems amplify and complexify cognition—but they are not its origin. From an evolutionary perspective, cognition is grounded in agency, not anatomy. What matters is not the presence of neurons, but the capacity to coordinate behavior in adaptive, self-organizing ways.

6. The Evolutionary Roots of Agency

In mainstream discourse, “agency” is often equated with the conscious deliberation of human minds. We associate it with intention, choice, and rational autonomy. But this anthropocentric framing risks confusing the product for the process. Human agency, in all its complexity, did not appear suddenly—it evolved from more fundamental forms of biological agency that long predate nervous systems or reflective thought.

At its core, agency refers to the capacity of a system to initiate and regulate actions in ways that serve its continued existence. It is not about free will or self-awareness, but about autonomy, purposiveness, and organized responsiveness. On this view, agency is not the exception in life—it is the rule. From bacteria navigating chemical gradients to plants orienting toward light, life entails the constant enactment of goal-directed behavior in response to changing conditions (Kauffman, 2000; Moreno & Mossio, 2015).

Biological agency emerges from the thermodynamic imperative to resist entropy: living systems must maintain their internal order through active processes of self-construction, repair, and regulation (Maturana & Varela, 1980). This imperative gives rise to basic forms of purposiveness—not imposed from outside, but generated from within the system. A cell’s membrane, for example, is not just a physical boundary—it is an active interface that distinguishes self from environment, modulates interaction, and sustains viability.

These forms of agency are not mere metaphors. They are operational descriptions of how organisms maintain themselves through coordinated internal processes and environmentally sensitive behavior. Importantly, such agency is scale-sensitive and relational: it is not housed in a single molecule or gene, but arises from system-wide organization (Barandiaran, Di Paolo, & Rohde, 2009).

What we call cognition in humans—language, abstract reasoning, imagination—builds upon this deeper substrate of organismic responsiveness. Brains do not create agency; they amplify and elaborate it. The roots of our own capacities lie in metabolic regulation, sensorimotor coordination, and adaptive behavior shared with simpler organisms (Lyon, 2006; Di Paolo et al., 2017). Even in animals with nervous systems, much of behavior is organized sub-personally—by the body, the cells, the tissues—rather than by conscious choice.

Understanding the evolutionary continuity of agency has critical implications. It refutes the idea that mind is a radical departure from biology. Instead, it shows that mind, like life itself, is processual, emergent, and grounded in the logic of self-organizing systems. The mind does not stand outside nature—it is one of its most complex expressions.

7. Naturalized Purpose: Plants and the Biological Imperative

Living systems exhibit purposeful behavior, yet in many cases—especially in plants—this occurs without intention or mental representation. Understanding this purposiveness requires reframing what we mean by “purpose” in biology. Rather than importing human mental models, the APS framework defines purpose through the concept of the biological imperative: the evolved, intrinsic drive of living systems to maintain themselves, grow, adapt, and reproduce. This imperative is not imposed from outside but emerges from the system’s internal organization and its functional relation to its environment.

At its core, the biological imperative is the expression of a system’s continued self-production and self-maintenance—what Maturana and Varela (1980) called autopoiesis. A plant root foraging for nutrients, a vine turning toward light, or a seed germinating in response to moisture all act in ways that serve their own continued viability. These are not chance events or mechanical responses—they are coordinated, adaptive, and functional. Purpose, in this view, is not a projection but an organizing principle grounded in the logic of living systems.

The biological imperative differs fundamentally from externally assigned goals or conscious intentions. It is enacted through the interplay of metabolic processes, signaling networks, and environmental engagement. Importantly, these goal-oriented behaviors arise at all levels of biological organization. In plants, this includes tissue-level regulation, intercellular signaling, and whole-organism responses to variable conditions. Such coordination illustrates how purposiveness is distributed rather than centralized—emerging from system-level integration, not cognitive command.

The APS framework clarifies that this kind of purposiveness is not metaphorical. Plants are not “like” purposeful agents—they are purposeful, by virtue of their evolved structure-function relationships. This naturalized view avoids anthropocentric assumptions while preserving scientific explanatory power. As Dennett (2017) argues, recognizing “competence without comprehension” allows us to attribute function and goal-directedness without invoking minds.

Moreover, the biological imperative helps to differentiate biological systems from machines. Unlike engineered systems, which are purpose-designed from the outside, living systems evolve their own means to sustain themselves. Their structure is both the product and the enabler of their ongoing activity. As Kauffman (2000) noted, this makes living systems self-constructing and self-justifying—their function and form co-evolve in pursuit of viability.

In the case of plants, this purposiveness is often missed precisely because it is not mentalistic. Yet, as this framework emphasizes, mental representation is not required for purposeful behavior. What matters is that the system maintains a coherent, functional relation to its environment, guided by an internally driven imperative to persist and propagate.

8. Is Plant Behavior Just a Metaphor?

The increasing use of terms like “plant learning,” “memory,” or “decision-making” has drawn criticism from some scientists and philosophers, who argue that these descriptions anthropomorphize non-sentient organisms. But such critiques often rest on a misunderstanding of how language functions in biological explanation. When used carefully, cognitive terms are not metaphorical in a misleading sense—they are functionally descriptive, capturing real behavioral patterns that reflect adaptive, goal-directed activity.

In biology, functional language describes what organisms do in terms of outcomes and effects, without implying they possess minds like ours. When researchers say a plant “chooses” between light sources or “remembers” a stressor, they are not suggesting consciousness or deliberation. Rather, they are identifying repeatable, testable behaviors that demonstrate internal regulation and responsiveness to environmental context—behaviors that unfold over time and exhibit continuity, as seen in studies of plant habituation (Gagliano et al., 2014) or light-preference reversals (Trewavas, 2005).

These descriptions reflect a key functional likeness between humans and plants: both process information and act in ways that enhance their viability. The similarity is not structural but behavioral—rooted in the shared property of biological agency. While humans and plants differ in their mechanisms, both pursue the same fundamental ends: to survive, reproduce, and flourish. Recognizing this does not anthropomorphize plants; it acknowledges a basic feature of all living systems.

The APS framework reinforces the legitimacy of this vocabulary. Biological systems, including plants, exhibit context-sensitive, adaptive behavior organized toward sustaining life. Describing such activity in cognitive terms reflects these functional capacities—not an attribution of mental states. As Dennett (1987) argued, adopting the intentional stance is valid when it enhances explanatory and predictive power and remains grounded in observed behavior.

Importantly, this use of cognitive terms is not unique to plant science. Across biology, we describe immune systems as “recognizing” pathogens, cells as “deciding” to divide, or bacteria as “remembering” environmental conditions. These are not anthropomorphic errors but concise ways of describing complex regulatory functions with clear empirical grounding.

Critics often mistake the understanding of biological goals through human cognition for the existence of those goals in human minds alone. But non-human organisms demonstrate agency through their behavior, which can be empirically investigated without invoking consciousness. The metaphor arises from our attempt to describe systems that operate in goal-directed, information-sensitive ways—not from a belief that plants think like us.

Rejecting all cognitive language in plant biology risks reinforcing a narrow view of cognition as exclusively neural. Yet many theorists argue that cognition should be defined more broadly—as the capacity to process and act on information in ways that sustain the organism (Calvo & Friston, 2017; Lyon, 2006). On this view, plants qualify as cognitive agents—not metaphorically, but biologically.

The question, then, is not whether plant behavior is “just a metaphor,” but whether our language accurately tracks biological reality. When cognitive terms clarify, explain, and predict the adaptive behavior of living systems, they advance science—not sentimentality.

The use of terms such as agent-like, intelligent-like, or mind-like reflects a transitional stage in the naturalization of cognitive concepts. These expressions do not imply that biological systems only resemble agency or intelligence metaphorically. Rather, they mark a conceptual distinction: the phenomena in question are real and empirically grounded, but differ from their human, conscious counterparts. The “-like” suffix signals that these forms of agency or cognition are functionally genuine, yet non-representational and non-mental. As biological concepts are disentangled from their anthropocentric origins, such terms may be used literally—without qualification—to describe the mindless, purposive organization intrinsic to living systems.

9. Distributed Cognition in Plants

In contrast to animals, plants lack a central nervous system. Yet they still manage to coordinate complex, goal-directed responses to their environment. How is this possible? The answer lies in their distributed cognitive architecture—a system of decentralized, networked communication that allows plants to sense, process, and respond to information across their entire body.

Plant cognition is not localized in a brain-like organ. Instead, it emerges from the dynamic interactions of cells, tissues, and signaling pathways. For example, root apices have been shown to act as sensory and integrative hubs, detecting chemical gradients, mechanical resistance, and water availability, and adjusting growth accordingly (Baluska et al., 2004). Similarly, leaves engage in local sensing and systemic signaling, contributing to the plant’s overall capacity to evaluate threats or optimize photosynthesis.

This decentralized intelligence is made possible by complex biochemical networks. Electrical signals, hormonal gradients (like auxin or jasmonates), and even action potentials allow different plant parts to communicate and coordinate (Fromm & Lautner, 2007; Toyota et al., 2018). These signals are not merely reactive; they contribute to anticipatory, state-dependent behavior. For instance, a plant under herbivore attack can warn distant tissues—or even neighboring plants—before damage occurs, adjusting physiology in advance.

Such distributed information processing is increasingly being recognized as a form of non-neural cognition. As Calvo, Sahi, and Trewavas (2020) argue, cognition should not be equated with neural anatomy but instead defined functionally—as the ability to acquire, integrate, and act on information in an adaptive way. On this view, plants qualify as cognitive organisms not despite their lack of a brain, but because of the ways their entire bodies serve as sites of intelligent regulation.

The APS framework reinforces this interpretation. It treats agency as a product of multiscale coordination—not as something imposed from a central locus, but as emergent from the organism’s organization. Plant behavior exemplifies this: decision-making occurs not in a central control center, but through distributed consensus across tissues and scales. The resulting behaviors—directional growth, immune responses, circadian timing—are unified, functional, and adaptive.

Importantly, distributed cognition is not unique to plants. Social insects, bacterial colonies, and neural networks also exhibit forms of intelligence that emerge from decentralized interactions. In this broader biological context, plants demonstrate how cognitive capacities can evolve through entirely different architectures, highlighting that centralized brains are not a prerequisite for intelligent behavior.

Recognizing distributed cognition in plants challenges outdated assumptions about the link between intelligence and anatomy. It invites a more inclusive, functional understanding of cognition—one that acknowledges the diversity of strategies life has evolved to solve problems, adapt to uncertainty, and act in the world.

10. The Limits of Neurocentric Thinking

The long-standing assumption that cognition requires a brain has led to a powerful yet limiting neurocentric bias in biology. Intelligence, perception, memory, and decision-making are often defined in terms of nervous systems—especially human ones. This framework reinforces the idea that only organisms with brains can think, learn, or act intentionally. But this view is increasingly at odds with the evidence emerging from plant biology and other non-neural life forms.

Neurocentrism treats the brain as both the source and the measure of cognition. It underpins definitions of intelligence that prioritize central processing, neural complexity, and behaviors that mirror human problem-solving. While useful in neurobiology and psychology, this model fails to account for the many ways that non-neural organisms—including plants, fungi, and bacteria—sense, process, and act on information in adaptive, functional ways.

Plant biology offers some of the strongest counterexamples to this assumption. Plants can detect light gradients, remember past stressors, anticipate environmental change, and modify growth patterns based on integrated information from multiple sources. These are not random reactions but coordinated, adaptive responses that meet the functional criteria for cognition (Trewavas, 2003; Calvo & Keijzer, 2009). The absence of a nervous system does not imply the absence of intelligence—it simply reflects a different organizational architecture.

The problem with neurocentrism is not just conceptual. It also distorts research priorities. As Calvo and Friston (2017) note, “Neurocentrism narrows our scope of inquiry to phenomena that resemble brain-based intelligence, potentially blinding us to more general principles of biological cognition.” If cognition is defined only in neural terms, entire domains of living intelligence are dismissed as metaphor, instinct, or reflex.

The APS (Agency–Process–Scale) framework explicitly counters this bias by grounding cognition in biological agency rather than neural anatomy. From this perspective, cognition is not about having a brain, but about having the capacity to act in ways that are responsive, purposeful, and coordinated across biological scales. Plants clearly meet this standard. Their behavior is not noise—it is organized, goal-directed, and modifiable based on internal state and external context.

This broader view of cognition aligns with recent developments in enactivist and ecological theories of mind, which emphasize that intelligence arises through the dynamic coupling of organisms with their environments (Varela, Thompson, & Rosch, 1991). It also resonates with findings from synthetic biology and bioengineering, where even minimal systems can display primitive forms of learning or goal-directed behavior.

In short, the limits of neurocentric thinking are the limits we impose on ourselves by mistaking anatomy for function. By rethinking cognition as a capacity grounded in agency, organization, and interaction—not neural circuitry—we gain a clearer, more inclusive picture of life’s intelligence.

11. Plant Agency in Ecosystems

Plant agency does not end at the boundary of the individual organism. Plants are embedded in ecological networks where their actions influence—and are influenced by—other organisms, resources, and environmental conditions. Far from being passive background organisms, plants are dynamic participants in shaping ecosystems. They engage in competitive and cooperative interactions, modulate their own environments, and display what can only be described as system-level intelligence.

Agency at this level becomes relational: plants do not act in isolation, but as part of distributed ecological systems that include microbes, fungi, animals, and even other plants. Root exudates, for example, alter the microbial composition of the rhizosphere to enhance nutrient uptake or suppress pathogens—an act of selective environmental engineering (Bais et al., 2006). Mycorrhizal networks allow plants to share information and resources, forming complex underground systems often dubbed the “wood wide web” (Simard et al., 1997; Gorzelak et al., 2015). These networks can support kin selection, resource redistribution, and even warning signals in response to herbivory, functioning as decentralized information hubs.

Such dynamics reveal a form of collective agency—plants not only respond to their environment but actively shape it in ways that promote long-term survivability. This includes altering microclimates, soil composition, and nutrient cycles. Some species act as ecological engineers, transforming barren landscapes into viable habitats for other organisms. The success of entire ecosystems can hinge on the feedback loops initiated by plant behavior.

From an APS (Agency–Process–Scale) perspective, these ecosystem-level processes exemplify how plant agency scales up through dynamic interrelations. What begins as local responsiveness (to light, gravity, water, etc.) becomes a pattern of action that transforms habitats and reshapes community dynamics. This system-level intelligence is emergent, non-neural, and highly adaptive. It challenges anthropocentric models that limit agency and cognition to centralized control or conscious intention.

Moreover, plants engage in selective partnerships that reveal strategic ecological behavior. Legumes, for instance, form symbioses with rhizobia bacteria that fix nitrogen in exchange for carbon, but they also regulate and penalize non-cooperative strains (West et al., 2002). This shows that even mutualistic behavior involves monitoring, choice, and regulation—all key components of functional agency.

Understanding plants as ecosystem agents also offers a better lens for conservation. When viewed as active participants rather than passive resources, plants emerge as integral contributors to biodiversity, climate regulation, and ecosystem resilience. Protecting them is not just about preserving a species—it’s about preserving functional intelligence at the system level.

12. Overcoming Human Cognitive Bias

The challenge of recognizing plant cognition ultimately confronts a deeper issue: our own cognitive limitations. We are evolutionarily primed to identify intelligence in forms that resemble us—those that move, emote, and possess brains. As a result, we routinely overlook or diminish life forms that lack these familiar features. This human-centered bias limits our ability to perceive the true diversity of cognition and agency in the natural world.

Throughout this series, we have seen that plants exhibit behaviors—perception, communication, learning, memory, and even decision-making—that fulfill functional definitions of cognition. Yet these capacities are often dismissed because they do not align with our inherited assumptions about what intelligence should “look like.” This is not a failure of plants to be intelligent, but a failure of our conceptual tools to detect intelligence where it is not shaped in our image.

The APS (Agency–Process–Scale) framework offers a corrective to this bias. By rooting cognition in biological function rather than in anthropomorphic templates, APS redefines intelligence not as a centralized property of brains, but as a capacity to process information, regulate activity, and coordinate purposeful action across scales. From this standpoint, cognition is not a privilege of animals but a general feature of life—expressed through different mechanisms in different organisms.

This reorientation allows us to move beyond superficial metaphors without collapsing into vague generalities. Plants do not think like humans or animals, but they do engage in biologically meaningful behaviors that satisfy criteria for agency and cognition. They sense their surroundings, respond in adaptive ways, and alter their developmental and ecological strategies based on integrated information. These capacities are real, observable, and scientifically tractable.

Recognizing this does more than rehabilitate plants in our conceptual ecology—it challenges the neurocentric and anthropocentric assumptions embedded in biology itself. It opens space for new forms of explanation that are better aligned with how life operates: dynamically, relationally, and across multiple scales of organization. It also compels us to reconsider long-standing dichotomies between mind and matter, action and reaction, cognition and instinct.

In the end, the question is not whether plants are “just like us.” They are not—and they don’t need to be. The more pressing task is to develop frameworks that allow us to understand life on its own terms. APS offers one such path, uniting agency, process, and scale in a coherent account that restores meaning, function, and purpose to biological systems without reverting to outdated vitalism or projection. In doing so, it helps biology become more than a catalog of mechanisms. It becomes a science of living systems.

Rethinking Cognition

Functional Equivalence – a scientific lens

A central obstacle in interpreting plant cognition is the widespread misconception surrounding functional equivalence. In biological systems, functional equivalence refers to the emergence or persistence of similar adaptive outcomes—such as movement, coordination, perception, and regulation—despite divergence in structural or mechanistic pathways. These outcomes may arise through distinct genetic, developmental, or physiological means, yet fulfill analogous roles that are critical to survival and environmental responsiveness (Moroz & Romanova, 2024). Such equivalence is not superficial, but instead a product of evolutionary processes: either through convergent evolution, where unrelated taxa independently develop similar solutions to shared challenges, or divergent evolution, where homologous traits are redeployed in novel ways (Wake, 1999; Hall, 2012b). For instance, wings in birds, bats, and butterflies all enable flight, despite arising from entirely different anatomical structures.

A Functional Evolutionary Framework for Analogical Reasoning

Functional equivalence justifies analogical reasoning from an evolutionary perspective. Traits that solve similar adaptive problems may be meaningfully compared even if their structural origins differ. This approach permits the inference of cognitive-like capacities in plants without assuming neural architecture. These comparisons are not analogies in metaphor alone, but become methodologically robust when grounded in evolutionary function under selection (Moreno & Mossio, 2015). Cognition, when reconceived as functional regulation and responsiveness, is decoupled from neuron-centric definitions and made accessible to structurally diverse life forms.

Function Before Form: Shifting Scientific Focus

Functional biology prioritizes adaptive performance over lineage. Traits endure not because they conform to a predefined design, but because they causally contribute to reproductive success and survival within specific ecological contexts (Moreno & Mossio, 2015). Evolution is better understood as constrained functional exploration—a dynamic interplay of phenotype, performance, and feedback across developmental and environmental scales (West-Eberhard, 2003). Systems biology reinforces this reframing, showing how genetic networks, physiological systems, and ecological relationships interlink into flexible, multiscale architectures capable of achieving functional goals despite structural diversity (Kitano, 2002).

Mechanisms Enabling Functional Equivalence

Several evolutionary mechanisms illuminate how structurally dissimilar systems produce functionally similar outcomes:

Developmental plasticity, the capacity for diverse developmental trajectories to reach convergent functional endpoints, demonstrates that biological pathways are context-sensitive and adaptable (Pigliucci, 2001; Jablonka & Lamb, 2005).
Structural constraints, particularly conserved regulatory genes such as those in the Hox family, preserve functional organization across taxa despite variation (Carroll, 2005).
Convergent evolution is seen in traits like echolocation, which independently emerged in bats and dolphins to solve parallel perceptual challenges (Jones & Teeling, 2006).
Adaptive trade-offs reflect the balancing of competing selective pressures to maintain overall viability (Stearns, 1992).
Modularity and redundancy provide resilience and flexibility—characteristics that enable systems to reconfigure functionality in response to internal or external disruptions (Hartwell et al., 1999; Jeong et al., 2000).

These mechanisms collectively illustrate that function does not require structural uniformity; what matters is how components contribute coherently to systemic viability in context.

Plants as Cognitive Agents: functionally defined cognition

When cognition is defined in functional terms—as a system’s capacity to regulate, respond, and integrate environmental information—plants demonstrate significant cognitive analogs. Their behaviors are mediated through chemical gradients, hormonal integration, morphological adaptation, and stress-responsive signaling (García, 2015; Levin, 2023b). Though these systems differ structurally from animal nervous systems, they fulfill comparable roles in adaptive regulation. Bacterial chemotaxis and plant phototropism, for example, both facilitate directional responsiveness, albeit through distinct architectures (Wadhams & Armitage, 2004; Garzón & Keijzer, 2011). Similarly, root–shoot coordination in plants mirrors hormonal regulation seen in animal systems. These examples typify cognitive equivalence—diverse systems converging on strategies that enable adaptive coherence.

Internal Reference Frames and the APS Model

Fields and Levin (2020) propose that all living organisms maintain internal reference frames—dynamic, biologically instantiated systems that orient perception and behavior at multiple scales. These reference frames, though structurally varied, are functionally equivalent in sustaining coherent responsiveness. The Agency–Process–Scale (APS) framework articulates cognition as an emergent property of distributed agency rather than neuron-based processing. It emphasizes scale-sensitive integration and system-level coherence as hallmarks of cognitive behavior.

Agency as Coherence: Evolutionary Implications

Functional equivalence also supports a processual understanding of biological agency. Organisms do not simply react passively to stimuli; they restructure internal processes and coordinate behavioral strategies with purposive responsiveness (Emirbayer & Mische, 1998; Laland et al., 2016). Microbial quorum sensing exemplifies this: it enables collective decision-making through signal integration and population-level coordination, functionally akin to group cognition (Miller & Bassler, 2001). Within the APS framework, agency is defined by the capacity to sustain coherence across developmental, behavioral, and evolutionary timescales, linking structure and function to meaning and action.

Toward a Pluralistic View of Cognition

Embracing functional equivalence provides a scientifically grounded, non-anthropocentric view of cognition. It permits the recognition of cognitive agency in systems lacking neurons, by focusing on systemic regulation, adaptive integration, and functional responsiveness. Plant cognition, framed this way, is not metaphorical but biologically legitimate. Analogical reasoning becomes a tool for uncovering functional parallels across life forms, supporting a pluralistic cognitive science that honors diversity in structure while revealing deep commonalities in adaptive function.

Empirical Research

A growing body of empirical research supports the view that plants exhibit behaviors suggestive of learning, memory, and anticipatory action. Experiments by Gagliano and colleagues (2014), for instance, showed that pea plants can associate a neutral cue (a fan) with light direction in a classical conditioning paradigm. Other studies demonstrate long-distance electrical signaling, root-foraging decisions, kin recognition, and modular memory-like responses to repeated stimuli. While these behaviors lack neurons, they often involve calcium signaling, hormonal cascades, and feedback loops, suggesting decentralized but integrative control systems. These findings support claims of minimal cognition grounded in the plant’s capacity to integrate environmental cues, modulate internal states, and adjust behavior accordingly.

Comparative Functional Analysis

The operational consequences of functional equivalence for the study of plant cognition are outlined in Spencer (1925) and reproduced here:

Comparative functional analysis of plant cognition draws on tools from neurobiology, molecular biology, behavioral ecology, computational modeling, and systems science. This interdisciplinary approach seeks to understand how plants perceive, process, and respond to environmental information through adaptive and coordinated behavior—without relying on a nervous system.

Electrophysiological Methods

Action Potential Measurement: Microelectrodes have recorded rapid electrical signaling in Mimosa pudica and Dionaea muscipula, revealing plant action potentials that are functionally analogous—but not homologous—to animal neurons (Brenner et al., 2006).

Long-Distance Signaling: Wounding in Arabidopsis thaliana initiates systemic electrical signals mediated by glutamate receptor-like channels, indicating plant-wide communication networks (Volkov, 2012; Toyota et al., 2018).

Molecular and Biochemical Techniques

Gene Expression Profiling: RNA sequencing and qPCR have identified transcriptional responses associated with stress memory and priming in various species (Crisp et al., 2016).

Proteomics: Proteomic assays track signaling cascades such as jasmonate and salicylic acid pathways involved in herbivore defense and environmental responsiveness (Gagliano, 2017).

Neurotransmitter Analog Assays: Detection of signaling molecules like glutamate, GABA, and ethylene demonstrates functional parallels to neural communication (Baluška & Mancuso, 2013; Mousavi et al., 2013), though their roles in plants are structurally and evolutionarily distinct.

Behavioral Experiments

Habituation Tests: Mimosa pudica demonstrates a form of non-associative learning, suppressing leaf-folding responses after repeated non-harmful stimulation—suggestive of behavioral plasticity (Gagliano et al., 2014; Trewavas, 2014).

Associative Learning: In a controversial but peer-reviewed study, Pisum sativum seedlings appeared to anticipate nutrient directionality based on light cues, suggesting rudimentary associative learning (Gagliano, 2017). These results remain under debate and require further replication.

Imaging and Microscopy

Calcium Imaging: Fluorescent dyes visualize calcium waves that propagate across cells in response to mechanical or chemical stimuli, providing insight into intracellular signaling dynamics (Baluška & Mancuso, 2013).

Structural Imaging: Microscopy reveals dynamic root and shoot modifications in response to environmental changes, supporting the study of adaptive growth plasticity (Karban, 2015).

Computational Modeling

Network Analysis: Models of root and mycorrhizal interactions explore decentralized communication and resource allocation, resembling decision-making systems in distributed networks (Trewavas, 2014).

Machine Learning: Algorithms analyzing growth patterns and chemical responses can reveal non-random, adaptive behavior patterns across environmental contexts (Gagliano, 2017).

Ecological and Evolutionary Approaches

Symbiosis Studies: Mycorrhizal and rhizobial partnerships demonstrate resource-sharing strategies and signal coordination, interpreted as cooperative decision-making processes shaped by evolutionary pressures (Karban, 2015).

Allelopathy and VOC Communication: Plants modulate neighboring growth via root exudates and volatile organic compounds, supporting functional parallels to environmental information processing (Brenner et al., 2006; Parise, Gagliano & Souza, 2020; Marder & Parise, 2023).

Controlled Laboratory Studies

Model Organisms: Arabidopsis thaliana and Pisum sativum are widely used in studies of stress memory, plasticity, and responsiveness, providing genetically tractable platforms for investigating cognitive-like functions (Crisp et al., 2016).

Statistical Validation: Increasing use of controlled experimental designs, blinded trials, and statistical rigor has improved reproducibility and empirical robustness in plant behavior research (Trewavas, 2014).

Substrates of Behavioral Coordination in Plants

Although lacking neurons, plants integrate multiple physiological systems to support adaptive responses across contexts. These systems provide a biologically grounded basis for studying plant cognition as distributed, embodied, and process-based.

Sensory Systems: Photoreceptors, mechanoreceptors, and chemoreceptors detect light, touch, and chemical cues, often modulated by hormone signaling networks (Baluška & Mancuso, 2013).

Vascular and Transport Systems: The phloem and xylem enable systemic coordination by distributing water, nutrients, hormones, and electrochemical signals (Volkov, 2012).

Signal Transduction Pathways: Hormones such as auxins, gibberellins, abscisic acid, and jasmonates mediate adaptive responses to biotic and abiotic stimuli (Gagliano, 2017).

Electrical Signaling: Plants propagate electrochemical signals via specialized cells that coordinate rapid defense and communication responses (Toyota et al., 2018).

Memory and Learning Mechanisms: Epigenetic modifications, stress priming, and gene expression plasticity contribute to environmentally informed, temporally extended responses (Crisp et al., 2016).

Environmental Interaction and Communication: Plants shape and respond to their environments through volatile signals, allelopathic chemicals, and symbiotic networks—actively constructing selective niches (Karban, 2015; Parise et al., 2020; Marder & Parise, 2023).

Growth Patterns and Movement: Tropisms, thigmotropism, and differential growth reflect the integration of diverse signals into coordinated behavioral strategies (Trewavas, 2014).

While the study of plant cognition is still evolving and some claims remain contested, the multidisciplinary evidence supports the view that plants exhibit context-sensitive, adaptive behaviors grounded in complex signaling, integration, and responsiveness. By avoiding anthropocentric assumptions and focusing on functional organization, plant cognition can be studied rigorously as a biological phenomenon emerging from the systemic capacities of living organisms.

Glossary of biological and cognitive agency

This glossary provides a dual-perspective interpretation of key terms commonly used in the context of human intentional psychology and cognitive science. Many of these words—such as agency, intelligence, and communication—are typically defined in relation to uniquely human mental capacities, such as language, reasoning, and self-awareness. However, these capacities are evolutionary developments of more general biological functions shared across living systems.

By distinguishing between cognitive (human-specific) and pre-cognitive (biologically general) meanings, this glossary aims to clarify how the language of human psychology can be naturalized and extended to non-minded organisms. For example, while humans learn through conscious reasoning, other organisms—such as plants—also acquire and process information that improves their capacity to survive, reproduce, and adapt, even in the absence of consciousness.

This dual framing respects the semantic richness of cognitive terms while grounding them in the broader context of biological agency. It reflects a growing scientific recognition that many features we once considered uniquely human—such as learning, memory, or even forms of reasoning—have functional analogues in other forms of life. Understanding these continuities helps us articulate a more coherent and biologically inclusive science of agency, intelligence, and adaptation.

Glossary

The glossary below maps narrow-sense terms from human cognition (plain text) onto their broad-sense, biologically grounded counterparts (italics), grouping cognitive capacities by functional domains such as perception, learning, and decision-making. This approach reveals how cognition emerges from and scales with life’s regulatory complexity (Lyon, 2006; Levin, 2023a), highlighting functional continuity across biological scales. For example, prediction spans from chemotactic responses in bacteria to behavioral foresight in animals—differing mechanistically but converging in adaptive purpose (Fields & Levin, 2020).

Rather than privileging neural architectures, this framing supports a naturalized view of cognition as an emergent property of self-organizing, self-regulating systems (Moreno & Mossio, 2015), consistent with the APS framework’s emphasis on agency enacted across scales.

Perception and Sensory Processing

Perception – The interpretation of sensory stimuli through cognitive processes, beliefs, and reasoning, shaping an individual’s understanding of the world. The processing of experiential information from the umwelt of a biological agent, guiding adaptive responses.

Attention – The ability to selectively focus on specific stimuli or information while filtering distractions. The biological capacity to prioritize sensory inputs and behavioral responses based on environmental relevance.

Sentience – Awareness of sensations, emotions, and subjective experiences. The ability to perceive and respond to stimuli, reflecting an organism’s sensitivity to its environment.

Anticipation, Learning, and Memory

Prediction – The ability to anticipate future events or conditions using patterns and accumulated knowledge. The biological mechanism that allows organisms to forecast environmental changes and adjust behavior accordingly.

Learning – The process of acquiring knowledge and skills for personal growth and adaptation. The ability to process and retain information that enhances adaptation and goal attainment.

Memory – The ability to store and recall information, experiences, and knowledge. The persistence of acquired information expressed through biochemical pathways, epigenetic imprinting, and behavioral patterns optimizing survival strategies.

Foresight – The ability to anticipate future events and make informed decisions based on experience, reasoning, and environmental awareness. The capacity to predict and prepare for future conditions using past experiences and environmental cues.

Executive and Adaptive Functions

Cognition – The mental processes involved in acquiring, processing, storing, and applying knowledge for understanding, reasoning, and problem-solving. The mechanisms by which organisms process, prioritize, store, and communicate information necessary for survival and adaptation.

Problem-Solving – The ability to identify challenges and develop solutions through logic, experience, and learning. The biological process of modifying strategies or behaviors to overcome environmental obstacles and ensure survival.

Decision-Making – The cognitive ability to choose between multiple options based on reasoning, experience, and desired outcomes. The biological mechanism by which organisms evaluate stimuli and select adaptive behavioral responses.

Reason – The mental faculty enabling logical analysis, evidence-based conclusions, and structured thought. The ability to process information in a manner that optimizes goal attainment and problem-solving.

Adaptation – The capacity to modify thoughts, behaviors, or strategies in response to environmental changes, challenges, or goals. Organisms alter structures, processes, and behaviors to survive, reproduce, and evolve, driven by physiological changes, genetic mutations, and newly developed survival strategies.

Agency, Intention, and Goal-Directedness

Agency – The human capacity for autonomous action, such as making independent moral judgments and deliberate choices. The exercise of goal-directed behavior essential for the biological imperative across all life forms.

Intention – A conscious mental orientation guiding actions toward a specific aim or desired effect. The observable goal-directed behavior of an organism responding to environmental stimuli and survival demands.

Goal – A desired outcome that directs intentional actions and decision-making. A biological agent’s adaptive objective, shaping behavior.

Value – The significance attached to something based on moral, ethical, cultural, or emotional considerations. The biological prioritization of stimuli, states, or behaviors based on their relevance to the biological imperative. Value is expressed through differential responsiveness, resource allocation, and behavioral bias, reflecting an organism’s internal norms and adaptive goals.

Integrative and Representational Capacities

Consciousness – Awareness of immediate experiences, including introspection, self-awareness, reasoning, memory, imagination, and abstract thought. The capacity of a biological agent to detect, process, and respond to spatial, temporal, and environmental conditions relevant to its survival and function.

Experience – The events encountered by an individual, often characterized by personal involvement, emotional depth, and uniqueness. The conditions encountered by an organism within its umwelt (subjective world), processed as information guiding behavior and adaptation.

Knowledge – Human awareness and comprehension of the world, encompassing subjective and objective understanding. Accumulated information about the conditions of existence used to guide decisions and adaptations.

Creativity and Communication

Creativity – The ability to generate new ideas, approaches, or solutions through imagination, experimentation, and innovation. The adaptive capacity to develop novel behaviors or responses that enhance survival and reproductive success.

Communication – The exchange of knowledge, emotions, and ideas through verbal and non-verbal means. The transmission of information via chemical, electrical, or mechanical signaling to facilitate interaction, coordination, and adaptive responses.

Historical context

From ancient times, plants have been personified and attributed with sentience or spirit. Such ideas, common in animist and folk traditions, persisted into early natural philosophy but were largely excluded from scientific discourse following the Scientific Revolution. Plants came to be seen as passive, inert matter—biological objects that lacked agency or awareness.

A major exception was Charles Darwin, whose final co-authored book The Power of Movement in Plants (Darwin & Darwin, 1880) proposed that root tips could guide behavior in a manner comparable to brain-initiated activity in lower animals. He noted that even without nerves or brains, plants responded to environmental stimuli:

“The course pursued by the radicle in penetrating the ground must be determined by the tip… It is hardly an exaggeration to say that the tip of the radicle thus endowed… acts like the brain of one of the lower animals” Darwin & Darwin, 1880, p. 573

Despite this, the idea of plant intelligence remained marginalized. Plants were widely regarded as non-agential, incapable of genuine responsiveness or intentional action—traits thought to require a central nervous system, and thus exclusive to animals.

This view began to shift in the mid-20th century as plant scientists uncovered complex systems of chemical and electrical communication. By the 1960s and 1970s, researchers had documented signal transduction pathways involving hormones, ion fluxes, and other mechanisms, laying the groundwork for a new understanding of plant responsiveness (Trewavas, 2003). The discovery of signaling compounds, long-distance electrical activity, and even vibration and sound sensing contributed to this shift.

In the early 2000s, Anthony Trewavas proposed that plants exhibit a form of intelligence expressed through behavior that enhances survival in a changing environment (Trewavas, 2003). He was joined by others, such as Monica Gagliano, whose experiments on learning and memory in plants provoked widespread debate (Gagliano et al., 2020).

The term plant neurobiology was popularized by Stefano Mancuso and František Baluška to emphasize the functional analogies between plant signaling systems and animal nervous systems (Baluška et al., 2006). Though plants lack neurons and synapses, they possess complex networks of signal integration that enable them to process information and respond adaptively.

This analogy was met with criticism. Many researchers cautioned that applying neural terminology to plants could be misleading, as plants and animals do not share homologous neural structures. The analogy is functional, not structural—plants exhibit convergent traits (analogies), not shared descent (homologies), in these signaling processes.

A parallel line of research approached the question behaviorally and ecologically. Without appealing to brains or neurons, scientists described plant behaviors—such as decision-making, memory, recognition, and learning—based on observable outcomes. This supported the idea that plants are cognitive agents in a biological, non-anthropocentric sense (Calvo et al., 2020).

Although lacking locomotion, plants are not passive. They actively regulate their internal states and interact flexibly with their environments. Pioneering studies by Jagadis Bose showed plants respond electrically to stimuli, though his ideas were dismissed at the time. Lyall Watson also speculated about plant awareness, but his claims were often considered pseudoscientific.

More recently, molecular biology and advanced imaging have revealed complex intracellular and intercellular signaling systems involving hormones, peptides, RNAs, and secondary messengers. Suzanne Simard’s work on mycorrhizal networks further highlighted underground signaling and cooperation among plants (Simard, 2022), prompting new conceptions of plant behavior at ecological scales.

Today, the study of plant perception and behavior incorporates sound, light, chemical, and tactile stimuli. Behavioral modeling using artificial intelligence and systems biology supports the view that plants process information in ways that satisfy scientific definitions of cognition.

Trewavas and colleagues at the University of Edinburgh’s Molecular Signaling Group proposed that plant intelligence is distributed across the organism, with local decision-making contributing to overall function. Trewavas (2016) wrote:

“Intelligent decisions are constantly required to optimize the plant phenotype… Spontaneity, counting to five, and error correction indicate intention… Volatile organic compounds may be the equivalent of language.”

He also cited a meta-study by Legg and Hutter (2007), which surveyed over 70 definitions of intelligence. They proposed that intelligence is:

(a) a property of an agent interacting with its environment,
(b) related to achieving goals, and
(c) dependent on adaptability.

These criteria align well with plant behavior in ecological and evolutionary contexts.

Trewavas concludes:

“Plant behavior is similar to cognition… A plant continually gathers and updates information, integrates this with internal state, and makes decisions to optimize fitness. Understanding plant behavior and intelligence has become one of the most exciting frontiers in plant biology” Trewavas, 2016

In recent philosophical analysis, Colaço (2022) challenges the literal use of cognitive terms, suggesting that anthropomorphic language may be metaphorical and unnecessary. However, he acknowledges that studying plant cognition can illuminate the nature of cognition itself, especially across species.

This aligns with the view advanced here: that cognition is a natural kind—a property expressed differently in different organisms depending on their evolutionary structure and scale. As a fundamental component of biological agency, cognition can be studied without invoking minds, brains, or human-like consciousness. It is grounded in the adaptive capacity of organisms to regulate behavior in relation to changing conditions—a central concern of the APS (Agency–Process–Scale) framework.

Summary & Conclusion

Plant cognition challenges our most basic assumptions about intelligence, purpose, and decision-making. Traditionally reserved for animals with brains, cognition is increasingly understood as a broader biological phenomenon. The Agency–Process–Scale (APS) framework contributes to this rethinking by offering a naturalized, non-anthropocentric account of how living systems sense, evaluate, and adapt to their environments. This article explores the core scientific and philosophical questions surrounding plant cognition and clarifies how the APS framework helps us make sense of these phenomena without projecting human mental attributes onto plants.

Cognition is often defined in terms of memory, learning, perception, and decision-making. But must these require neurons or minds? From an APS perspective, cognition is reframed as the functional capacity of living systems to coordinate their own internal processes and respond adaptively to their environments. Plants, while lacking nervous systems, demonstrate clear signs of this kind of functional cognition: they detect light and gravity, assess nutrient gradients, anticipate seasonal changes, and modulate growth in response to stress.

This perspective does not suggest that plants think or reason in a human sense. Instead, it emphasizes that plants possess sophisticated, evolved mechanisms for sensing and responding to complex conditions—capacities that are cognitive in the sense that they contribute to the regulation and persistence of the organism over time.

The APS framework distinguishes between biological agency and consciousness. Agency, as defined in APS, refers to a system’s ability to organize itself, respond adaptively, and maintain its own existence. This kind of purposiveness does not imply intention or awareness. It is grounded in the self-producing (autopoietic) and self-regulating capacities of living systems.

Human mental faculties—such as reasoning, imagination, or reflective awareness—are viewed as elaborations of these more basic agentive processes. Thus, while APS acknowledges that consciousness may emerge in certain complex animals, it is not necessary for cognition or purposive behavior. Plants are cognitive not because they are sentient, but because they act as autonomous agents within their environments.

Under APS, terms like “memory” and “decision” are used functionally. For example, plants may “remember” a prior drought condition through epigenetic or biochemical markers that influence future responses. Similarly, plants “decide” how to allocate resources based on integrated internal and environmental cues. These behaviors emerge from dynamic, multiscale feedback loops involving hormonal signaling, calcium waves, and electrical activity—not from mental representations or symbolic reasoning.

To avoid confusion, APS stresses the importance of functional equivalence over structural similarity. Plants do not have brains, but they do have decentralized signaling systems capable of coordinating behavior in ways that are evolutionarily adaptive.

A growing body of research supports the idea that plant behavior is complex, integrative, and adaptive:

Classical conditioning has been observed in pea plants trained to associate light direction with airflow (Gagliano et al., 2014).

Electrical signaling enables plants to coordinate rapid responses to herbivory or mechanical stress.

Root foraging behavior shows plants evaluating soil conditions and altering growth trajectories accordingly.

Priming and epigenetic memory allow plants to respond more effectively to recurring environmental challenges.

These findings support the claim that plants meet criteria for minimal cognition, even in the absence of neurons.

Skeptics argue that plant behavior is merely reactive and lacks the internal complexity associated with true cognition. APS addresses this by clarifying that cognition does not require internal symbolic representation, only the capacity to integrate information across time and space in a functionally meaningful way.

Terms like “reasoning” or “intelligence” can be misleading if they imply human-like faculties. APS therefore avoids metaphoric overreach by grounding its claims in biological mechanisms. The term “plant neurobiology” can be used descriptively to refer to plant electrophysiology but must be distinguished from actual neural systems.

By decoupling cognition from consciousness, APS provides a powerful framework for reinterpreting intelligence as a scalable property of life. It opens up new ways of thinking about the evolution of mind, the diversity of life strategies, and the nature of agency itself. Recognizing plants as cognitive agents encourages a shift in both philosophical and scientific worldviews, where intelligence is no longer confined to neural architectures or animal behavior.

This expanded view promotes a deeper appreciation of how all living systems organize, interpret, and act upon the world—not as passive machines, but as active participants in their own survival and evolution.

First published on the internet under the heading ‘Plant cognition’ in August 2023

. . . 18 August 2023 – substantial revision
. . . 25 August 2023 – first completion of logical flow from metaphor fallacy to agential function
. . . 31 August 2023 – refining ideas in preparation for removal of ‘Work in Progress’ symbol
. . . July 2025 substantial revision following the publication of Spencer 2025