origin & provenance - top/bottom working - shape
Many cultivar or clone forms of commercially available trees are vegetatively propagated by budding or grafting. In the UK most trees are bottom worked, budding the desired cultivar or clone onto a transplant of a related species, close to ground level, e.g. Sorbus aucuparia Sheerwater Seedling budded onto the rootstock of Sorbus aucuparia grown from seed. The bud is then trained to form the stem and crown of the desired cultivar. Top working, grafting the desired form at high level (typically 1.6 metres or higher) is not encouraged in this country except for certain weeping trees although it is more commonly used as a means of propagation throughout the rest of Europe.
All trees should be bottom worked unless otherwise specified.