Prayer of a Tree, Alexander L. Howard, A Manual of the Timbers of the World, 1920)
Trees and Shrubs are just a visual way to separate plants by the way that they grow. It is not a botanical definition. Wikipedia defines a tree as a “perennial plant with an elongated stem, or trunk, usually supporting branches and leaves.” A Shrub is just shorter with many branches. This means that you can transform a tree into a shrub or vice versa by careful pruning.