Moving stamens, better pollination: a floral strategy in the red-leaf Japanese barberry in Qufu, China

Berberis thunbergii 'Atropurpurea' dominates plant-ant interactions by touch-sensitive stamen movement, exploiting ants as mechanical actuators to repeatedly deliver pollen onto the stigma. Floral movements are an active and functionally diverse strategies that directly influence plant reproductive success, yet their specific roles in pollination across different plant species and environmental contexts remain underexplored. Here, we investigated the pollination process of red-leaf Japanese barberry (Berberis thunbergii 'Atropurpurea') in Qufu, China. We observed a sequence of active floral movements, including nectar presentation, staggered and prolonged dehiscence of pollen sacs both within a single anther and among different stamens, the lifting and forward unfolding of pollen sac valves, and a touch-sensitive response of the filaments. These movements facilitate self-pollination in the small shrub, with ants acting as mechanical agents that trigger filament flexion while foraging for nectar. Our findings demonstrate that plant pollination strategies are highly diverse and closely matched to both plant traits and environmental conditions. Moreover, they reveal that floral movements can serve as an active mechanism by which plants secure their own reproductive assurance.