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:
Abelia x 'Canyon Creek'
Abies firma, Japanese Fir
Abies holophylla, Manchurian Fir
Abies pinsapo 'Aurea', Golden Spanish Fir
Abies pinsapo 'Glauca', Blue Spanish Fir
Acorus graminus 'Ogon'
Acorus graminus 'Variegatus'
Adina rubella, Chinese Buttonbush
Aesculus flava, Yellow Buckeye
Aesculus pavia, Red Buckeye