Cherry trees can be distinguished from other species by their bark. Young trees and the younger branches on mature trees are clad in shiny smooth gray or brown bark that resembles satin. This bark is marked with scattered horizontal openings called lenticels, which are pores that facilitate a direct exchange of gases between the interior of the tree and the outside air. Lenticels have the equivalent function as stomata on plant leaves. Many plants and fruits have lenticels, but on cherry trees, they are particularly noticeable.