If they think of them at all, most people see plants as domestic accessories, with all the awareness of a Marcel Breuer Wassily chair. Gardeners and other plant lovers tend to see plants as horticultural eye candy, flaunting their pretty flower heads solely for our pleasure. Until very recently, even most scientists assumed that plants are essentially passive—rooted in place, taking whatever moisture, nutrients, and sunlight chance brings their way. It’s not exactly surprising, then, that the word “vegetable” is used to describe people with brain damage so severe they have no discernable awareness.
A trove of new research, however, is demonstrating that plants are far from botanical automatons. To be sure, researchers have found no signs of Socratic logic or Shakespearean poetry in the plant kingdom. But there is so much new data on plant intelligence—including abilities like sensing and, yes, even learning, remembering, and recognizing kin—that the investigation of plant intelligence is suddenly a serious scientific endeavor.
The latest case in point: You know the perennial debate over the role of nature vs. nurture—heredity or the environment—in the development of a human being? Studies have shown that, depending on their distinct personal experiences, identical human twins can have a different chance of getting a disease. Well, it turns out that in this respect plants may not be so different from people.
In a new study, University of Toronto biologists found that genetically identical poplar trees—clones—responded to drought differently, depending on the nursery the plants were obtained from. They took cuttings of the poplar clones from nurseries in two different regions of Canada and regrew them under identical climate-controlled conditions. Half of the trees were then subjected to drought. Since the trees were regrown under identical conditions, the researchers predicted all the specimens would respond to drought in the same manner, regardless of where they had come from. But low and behold, the genetically identical specimens responded differently to the drought treatment, depending on their place of origin.
Malcolm Campbell, one of the study’s authors, called the finding “quite stunning.” “A tree’s previous personal experience influences how it responds to the environment,” he said. In other words, the trees “remember” where they came from.
Discoveries such as this have the potential to transform the public’s view of plants. In fact, they’re helping to transform our understanding of the nature of intelligence itself.
They also have practical implications for gardeners, landscape designers, and foresters: The “memory” of previous experience discovered in this study could help determine how plants from a particular nursery will respond to conditions in a particular landscape. It may also help predict how certain plants will respond to climate change or other environmental stresses.