Stella Sandford writes:

It was once common, in Western societies at least, to think of plants as the passive, inert background to animal life, or as mere animal fodder. Plants could be fascinating in their own right, of course, but they lacked much of what made animals and humans interesting, such as agency, intelligence, cognition, intention, consciousness, decision-making, self-identification, sociality and altruism. However, groundbreaking developments in the plant sciences since the end of the previous century have blown that view out of the water. We are just beginning to glimpse the extraordinary complexity and subtlety of plants’ relations with their environment, with each other and with other living beings. We owe these radical developments in our understanding of plants to one area of study in particular: the study of plant behaviour.

The idea of ‘plant behaviour’ may seem odd, given the association of the word ‘behaviour’ with animals, including humans. When we think of classic animal behaviours – dancing honeybees, dogs wagging their tails, primates grooming each other – we may wonder what there could possibly be in plant life corresponding to this.

One early advocate of the importance of the study of animal behaviour was E S Russell, a biologist and philosopher of biology. In 1934, Russell argued that biology should begin with the study of the whole organism, and conceived the organism as a dynamic unity passing through cycles of maintenance, development and reproduction. These activities are, he said, ‘directed towards an end’ and it is this ‘directive’ activity that distinguishes living things from inanimate objects. Behaviour, according to Russell, was the form of this ‘general directive activity of the organism’ concerned with the relations of the organism to its external environment. This meant that plants quite as much as animals exhibit behaviours. But because plants are sessile (fixed in one place), behaviour is exhibited mainly in growth and differentiation (development of embryonic cells into particular plant parts), rather than in movement, as with animals.

By the end of the 20th century, our understanding of plant behaviour had expanded well beyond growth and differentiation, and it continues to expand. Plant behaviour is, as the botanist Anthony Trewavas puts it, ‘what plants do’. It turns out that they do a lot. [Continue reading…]