The line between whether a plant is a "tree" or a "shrub" is sometimes very thin and quite blurry! We use the following criteria to decide which type applies to a certain plant:
Asimina triloba, Paw Paw
Fagus grandifolia, American Beech
Illicium x 'Orion'
Illicium x 'Scorpio'
Loropetalum chinense 'Zhuzhou Fuchsia'
Viburnum plicatum 'Nanum'
Viburnum plicatum 'Summer Snowflake'