Indeed, we tend not to pay much attention to the immensely sophisticated sensory machines in the flowers and trees that can be found right in our own back gardens. While most animals can choose their environments, seek shelter in a storm, search for food and a mate, or migrate with the changing seasons, plants must be able to withstand and adapt to constantly changing weather, encroaching neighbors, and invading pests, without being able to move to a better environment. Because of this, plants have developed complex sensory and regulatory systems that allow them to modulate their growth in response to ever-changing conditions. An elm tree has to know if its neighbor is shading it from the sun so that it can find its own way to grow towards the light that’s available. A head of lettuce has to know if there are ravenous aphids about to eat it up so that it can protect itself by making poisonous chemicals to kill the pests. A Douglas fir tree has to know if whipping winds are shaking its branches so it can grow a stronger trunk. Cherry trees have to know when to flower.