Biologists have demonstrated that an exotic herb known as Mimosa pudica can learn and remember just as well as it would be expected of animals.
The nervous system of animals serves the acquisition, memorization and recollection of information. Like animals, plants also acquire a huge amount of information from their environment, yet their capacity to memorize and organize learned behavioral responses has not been demonstrated.
In Mimosa pudica—the sensitive plant—the defensive leaf-folding behaviour in response to repeated physical disturbance exhibits clear habituation, suggesting some elementary form of learning. Applying the theory and the analytical methods usually employed in animal learning research, we show that leaf-folding habituation is more pronounced and persistent for plants growing in energetically costly environments.
“Astonishingly, Mimosa can display the learned response even when left undisturbed in a more favorable environment for a month. This relatively long-lasting learned behavioral change as a result of previous experience matches the persistence of habituation effects observed in many animals,” the biologists wrote in a paper published online in the journal Oecologia.
“Plants may lack brains and neural tissues but they do possess a sophisticated calcium-based signally network in their cells similar to animals’ memory processes,” they explained.
The biologists concede that they do not yet understand the biological basis for this learning mechanism, nevertheless their set of experiments has major implications – not least, it radically changes the way we perceive plants and the boundaries between plants and animals, including our definition of learning as a property special to organisms with a nervous system function of a nervous system.