And they react to the buzzing of pollinators by sweetening their nectar.
When people pose the old question about whether a tree falling in an empty forest makes a sound, they presuppose that none of the other plants in the forest are listening in. Plants, supposedly, are silent and unhearing. They don’t make noises, unless rustled or bitten. When Rachel Carson described a spring bereft of birds, she called it silent.
But these stereotypes may not be true. According to a blossoming batch of studies, it’s not that plants have no acoustic lives. It’s more that, until now, we’ve been blissfully unaware of them.
The latest experiments in this niche but increasingly vocal field come from Lilach Hadany and Yossi Yovel at Tel Aviv University. In one set, they showed that some plants can hear the sounds of animal pollinators and react by rapidly sweetening their nectar. In a second set, they found that other plants make high-pitched noises that lie beyond the scope of human hearing but can nonetheless be detected some distance away.
After the team released early copies of two papers describing their work, not yet published in a scientific journal, I ran them past several independent researchers. Some of these researchers have argued that plants are surprisingly communicative; others have doubted the idea. Their views on the new studies, however, didn’t fall along obvious partisan lines. Almost unanimously, they loved the paper asserting that plants can hear and were skeptical about the one reporting that plants make noise. Those opposite responses to work done by the same team underscore how controversial this line of research still is, and how hard it is to study the sensory worlds of organisms that are so different from us.
The concept of floral communication has long been controversial, especially after decades of pseudoscientific (but very popular) claims about plants growing well to classical music or being attuned to human emotions. Those hokey claims “have never been substantiated by rigorous experiments,” says Richard Karban from the University of California at Davis, and they tainted the entire field of study, making scientists skeptical about the very notion of plants exchanging signals…
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