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:
Philadelphus lewisii 'Fallbrook'
Podocarpus macrophyllus 'West Lake'
Sequoia sempervirens 'Aptos Blue'
Sequoia sempervirens 'Atlanta'
Sequoia sempervirens 'Mount Loma Prieta Spike'
Smilax biflora var biflora