Abstract
It is more and more often acknowledged that plants are sensitive organisms which perceive, value, learn, remember, solve problems, make decisions and communicate to each other in actively acquiring information on their environment. However, the fact that many complex patterns of plant behaviour exhibit cognitive skills, usually ascribed to human and non human animals, has not been fully assessed. This article intends to show the theoretical obstacles which may have prevented experimenting on such behavioural/cognitive phenomena in plants.