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:
Magnolia x 'Stellar Ruby'
Mahonia x 'Beijing Beauty'
Osmanthus fragrans 'Tea Olive'
Osmanthus fragrans var. aurantiacus
Viburnum plicatum f. tomentosum 'Summer Snowflake'