Distributed Agency Without a Nervous System: Plant Intelligence, Memory, and Adaptive Constraint-Management.

This paper develops a theory of plant agency as distributed adaptive constraint-management without a nervous system. It argues that plants should not be understood as passive organisms merely reacting to stimuli, nor as conscious agents in the animal sense, but as decentralised living systems that perceive, integrate, remember, prioritise, and respond across body and environment. Plants detect light, gravity, humidity, temperature, nutrients, pathogens, herbivores, neighbours, salinity, drought, flooding, touch, microbial signals, volatile compounds, and mechanical damage. They coordinate responses through calcium waves, electrical signals, hydraulic changes, reactive oxygen species, hormones, volatile organic compounds, RNA movement, root exudates, mechanosensory pathways, and other signallin systems. These processes allow plants to allocate resources, alter growth, regulate stomata, prime immunity, recruit microbial partners, communicate danger, delay germination, flower, defend, and reorganise development under changing conditions.

Crucially, the paper defines plant agency through five capacities: perception, integration, valuation, memory, and action. This does not imply plant consciousness, animal-like intention, subjective experience, or mental deliberation. Rather, plant agency is treated as the capacity of a decentralised organism to sense changing conditions, integrate signals across tissues and timescales, prioritise competing biological demands, retain biologically useful traces of past events, and alter future form or activity accordingly. Plant memory is therefore not autobiographical recollection, but the retention of physiologically useful traces that shape later responsiveness. Stress memory, immune priming, vernalisation, circadian timing, developmental memory, and epigenetic effects are interpreted as forms of biological history without implying human-like remembrance.

Finally, the paper argues that plants are extended organism-environment systems. Roots modify soil chemistry, exudates shape microbial communities, fungi extend resource access, volatile compounds influence neighbouring plants and insects, and seeds carry maternal and environmental histories. Plant agency is therefore not detached action upon an environment, but continuous co-modification of body and surroundings. The paper connects this view to a broader theory of distributed intelligence and Paradox-Negotiation Theory: plants cannot maximise growth, defence, reproduction, water conservation, nutrient acquisition, and symbiosis all at once. They must continuously negotiate incompatible biological demands without collapsing into one rigid behaviour. In this sense, plant agency is not will or intention in the animal sense, but adaptive constraint-management across a living body. The result is a framework for understanding what forms of intelligence become possible when life solves problems without brains.