Platanus occidentalis, also known as American sycamore, American planetree, occidental plane, and buttonwood, is a species of Platanus native to the eastern and central United States. An American sycamore tree can often be easily distinguished from other trees by its mottled bark which flakes off in great irregular masses, leaving the surface mottled, and greenish-white, gray and brown. The bark of all trees has to yield to a growing trunk by stretching, splitting, or infilling; the sycamore shows the process more openly than many other trees. The explanation is found in the rigid texture of the bark tissue which lacks the elasticity of the bark of some other trees, so it is incapable of stretching to accommodate the growth of the wood underneath, so the tree sloughs it off.