When we hug a tree, nothing electrical happens – because we and the tree have the same voltage, that’s ascertained so far. But can’t trees sense human touch in at least some other way?
It just wants to protect itself
There is a phenomenon that can occur in young trees called thigmomorphogenesis, where the plant grows more slowly after being touched. For example, petting your home-grown tomatoes for just a few minutes each day will slow down their growth and create a thicker stem axis.
Wind triggers the same behavior pattern in plants: Lower height reduces the wind’s leverage on the roots, and thicker stems are more beneficial for stabilizing tomato plants. This of course also applies to movement caused by animals passing by, as less stable plants are prone to buckling. So it’s likely that tomatoes or other small trees have responses to this kind of exposure (and not just wind) in their genetic repertoire.
Scientists found that test specimens that were touched in this way produced more jasmonic acid. Not only does this acid alter height growth, it also irritates the plant, causing the stems to thicken and making the plant more stable. In particular, indoor plants that are exposed to too little light often have thin and unstable trunks. This phenomenon is even more obvious.
Young trees will develop thigmotropic morphology. Picture/Pexels
If you’re expecting a positive response from hugging a tree, this information will be disappointing. Because the aforementioned reaction is actually just a defensive strategy to fight against external influences that are not beneficial to the plant. Moreover, if trees are to sense anything from them, they must be able to feel pressure, they must be able to feel the arms surrounding their bark. A certain degree of pressure sensitivity does exist, but the range and size vary. For example, if an adjacent tree or a metal post presses against the trunk of a tree, the tree will begin to grow around the obstruction. However, the force exerted must be great and, above all, long-lasting—two factors that cannot be met by a human embrace. Large trees, in particular, also have thick bark. The bark is only composed of dead cells in the outer areas, so the feeling it can have is probably not much different from that of our hair.