What is a Root Collar, or Root Flair, on a Tree?
Simply put, the root collar, or root flair, is the heart system of the tree. It’s where the tree meets the earth and is the physical change of physiology from trunk to root. It's where the environment completely changes. Imagine for a moment that the soil is a whole universe on its own and that when you leave the soil, it's like leaving the planet and all the protection that comes with it. If specific parts of the plant are not at level and able to breathe, the tree will slowly suffocate and die. Not only this, but root flair creates deformities called girdling roots. These roots strangle the stem of the tree, and root flair gives the same symptoms as many other stress factors.