Of course, there may be another explanation for the apparent response to sound reported by Gagliano. One that could also account for the century of researchers and home gardeners (including Charles Darwin) who manipulated plant growth with music.
Could a sense of touch be why plants seem to respond to sound?
Even humans can perceive sound without hearing it, said Frank Telewski, a botanist at Michigan State University and an expert on how trees respond to wind.
"How many times have you sat next to someone who has their car stereo at full blast? You can really feel it pounding in your chest," he said.
Trees perceive and respond to touch, like wind or an animal passing on a trail. And like the wind, sound is a wave that travels through air.
In fact, a tree needs wind to grow, Telewski said. "If you stake down a seedling, you do it a little bit of disservice, because a tree needs to perceive motion. It's like physical therapy for the tree. If you stake it too tight, it does not allow the plant to produce stronger tissues."