 'Monstrosa' appeared from its leaf and short petiole to be 'Nana', while one cultivated in the Royal Botanic Garden Edinburgh in the early 20th century as 'Nana' appears from its leaf and long petiole to have been 'Monstrosa'.The current RBGE 'Nana' is the authentic wych clone (2017).The specimen of 'Nana' in the University Parks (North Walk), Oxford, UK, has attained a height of about 6 m (2017).