The results of an analysis of the spatial and age structure of the common birch in Eurasia – silver birch Betula pendula Roth and a unique representative of the European forest dendroflora – curly birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti and populations are reported, exhibiting significant differences between the plants. Numerous facts and observations (areas, spatial distribution, planting density, ecological niches, competitiveness, life forms, age groups, life expectancy) were analyzed, which showed significant differences between them. The authors believe that this, alongside other biological characteristics, is weighty evidence that curly birch is genetically determined separate from silver birch, and supports the earlier conclusion that curly birch qualifies as an independent species.