Growing

Although the roots do orient their growth to take advantage of the resources available in the soil, they are not completely independent of the rest of the tree, which in part dictates the anchoring job they must do.

For example, the group of trees in the background in this photo protect each other from the wind. But the American elm in the foreground is much more exposed to the wind. By producing hormonal cues, it can direct its roots' growth to meet its need for a stronger anchor than its neighbours. In cases like this, some roots grow in an I-beam shape to help them better withstand the stress.