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.
Some Plant Types are based on botanical differences (grasses, ferns, slime molds, fungus) while others are just arbitrary groups based on appearance (vines, trees, wildflowers) or popular interest (orchids, carnivorous plants).