The reason why I'm asking this question isn't because I've gone off the deep end and I now think plants talk to me, but rather because there has been a pretty interesting paper published called: Experience teaches plants to learn faster and forget slower in environments where it matters:Is this the beginning of the Day of the Triffids? Invasion of the Body Snatchers? Probably not, but it's still interesting.
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. InMimosa 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 favourable environment for a month. This relatively long-lasting learned behavioural change as a result of previous experience matches the persistence of habituation effects observed in many animals.