Botany defines trees as perennial and woody seed plants that have a dominant shoot axis that increases in size due to secondary growth of growth. These features distinguish a tree of shrubs, ferns, palms and other woody plants. In contrast to their developmental predecessors, most trees also have significantly more differentiated leaf organs, the multiple branched side shoots (long and short shoots) arise. The trunk, branches and twigs are elongated every year by the exudation of end and side buds, lignify and increase in size. In contrast to the shrub, it is a special feature of the trees that the end buds dominate over the lateral buds (apical dominance) and thereby form a predominant main instinct (acrotony).