PLANT MEMORY CIRCUITS. “There is a storage and recall memory based on a complex network of elements with a high degree of integration and feedback. The most important elements envisaged are calcium waves, epigenetic modifications of DNA and histones, and regulation of timing via a biological clock.”
http://onlinelibrary.wiley.com/doi/10.1111/j.1438-8677.2012.00674.x/abstract