From a BBC World Service Inquiry Program:

Professor Stefano Mancuso runs the International Laboratory for Plant Neurobiology at the University of Florence. In an experiment with two climbing plants, they found that both competed for a single support when it was placed between them. The plant that didn’t make it to the pole first immediately “sensed” the other plant had succeeded and started to find an alternative. “This was astonishing and it demonstrates the plants were aware of their physical environment and the behavior of the other plant. In animals we call this consciousness. We are convinced that plants are cognitive and intelligent.”

Aspen Grove, Lundy Canyon, Eastern Sierra, California – photo by Don Smith Photography, used with permission