Plants are social beings. When leaves from different plants touch each other, their roots send out signals, telling the other plant to get lost. New research from the Swedish University of Agricultural Sciences, published in PLOS One in May, found that maize seedlings whose leaves were touched give off chemicals via their roots, which cause non-touched maize seedlings to grow away from them.
Study co-author Velemir Ninkovic says the chemicals signal a crowded environment, so other plants choose environments with less competition and therefore more resources. Later on, seedlings exposed to these root chemicals also grow more leaves—a typical plant response to avoid being left in the shade.