Plants are clearly capable of all kinds of sensing — they can detect everything from changing levels of daylight to levels of the vital nutrient phosphorus in the soil, to signals from each other.

And when it comes to communication, plants have various methods at their disposal. Their sophisticated use of a suite of volatile organic chemicals (VOCs) could be considered a language, as varying groups of VOCs can be used flexibly in new interactions and new contexts. For example, a combination of different VOCs allows the plant to transmit information about attack by a herbivore. There’s even evidence for dialects among different species, and that plants that are more closely related understand each other better.

Plants can learn. Garden pea seedlings can learn that a sudden increase in airflow, caused by a fan, is followed by the occurrence of desirable blue light, and will then grow towards the fan.

Umberto Castiello at the University of Padua argues that it’s high time that plants regained their rightful place in the study of the psychology of non-human organisms.

In a paper published in the Journal of Comparative Psychology, Castiello gathers together a selection of recent evidence that plants can communicate, remember, recognise kin, decide and even count — “all abilities that one would normally call cognitive if they were observed in animals”. They can adapt to change, benefit from classical conditioning, and even come to make predictions about the future.

“The question should no longer be if plants are cognitive organisms but how plants make use of their cognitive capacities,” Castiello writes.