For much of the history of biology, plants were regarded as fundamentally passive organisms. Although they exhibited remarkable physiological complexity, they were generally interpreted as systems that simply grew, responded to stimuli, and executed genetically determined developmental programmes. Agency, purposeful behaviour, and adaptive decision-making were widely assumed to belong almost exclusively to animals.
Research over the past two decades has fundamentally altered this picture. Plants are now understood to coordinate electrical, hydraulic, chemical, and mechanical signalling, integrate information from multiple environmental sources, reorganise development throughout their lives, establish dynamic ecological partnerships, and continually regulate their own persistence under changing conditions. These discoveries have not merely expanded plant biology; they have challenged long-standing assumptions about the nature of life itself.
The importance of these findings extends beyond the study of plants. They demonstrate that biological agency does not depend upon brains, nervous systems, or animal-like behaviour. Instead, they reveal that agency is a more fundamental property of living organisation, expressed through whatever mechanisms enable organisms to maintain their viability.
APS regards this as one of the most significant conceptual developments in contemporary biology. Plants have shown that agency is not a specialised evolutionary innovation but a general organisational requirement of life. By separating agency from intelligence and recognising viability-oriented organisation as the common explanatory principle, plant biology provides a clearer understanding of what all living systems share despite their extraordinary diversity.
APS Principle: Plants changed biology by revealing that agency is a general property of living organisation rather than a specialised feature of animals.