A plant is a unified entity the organs of which carry out different functions and are joined by a vascular system which is able to integrate metabolism of a particular organ for the benefit of the whole plant. Thus by the end of the first vegetation season all birch groups form the same structural elements. However their quantity and the level of development differ. Namely, the following: 1) Betula pubescence show a tendency to the formation of higher stem and it's active radial growth provided by the development of a powerful assimilation apparatus and actively growing root system. 2) Typical features of curly birch (Betula pendula var.carelica Roth) are: high differentiation of plants in height, intensive formation of sylleptic shoots (in number and length) and specific weight of buds being higher than in two other groups of birches. Root system is notable for it's good developed net of thin rootlets. 3) Silver birch (Betula pendula) has a minimum contribution of the amount of shoots and buds to the total plant mass and along with this has a maximum biomass of stem in comparison to B. pubescence and curly birch.