If you’ve ever looked up at forest canopy (or a picture of one) you might notice distinct channels of daylight shining through between the treetops. This is because many trees grow in a phenomenal pattern referred to as “crown shyness”. The tree branches limit their own growth to avoid touching neighboring trees, which prevents the spread of disease and limits their risk of injury on windy days. Some trees even communicate threats to one another. When willows experience pest infestation, they emit a chemical signal that prompts nearby trees to produce more tannins that repel the insects.