The Karelian Birch: a Unique Biological Object

The paper summarizes the results of for more than 100 years of research by Russian and foreign scientists on an unusual and widely known representative of woody flora, the Karelian (aka Curly) birch Betula pendula Roth var. carelica (Mercklin) Hamet-Ahti. Their analysis shows that the key outcome of the decades of Karelian birch studies is the identification and description of its major biological characteristics: population and species–specific, anatomical–morphological, cytological, physiological–biochemical and molecular–genetic characteristics. Taken in their entirety, these characteristics make the Karelian birch a unique biological object, one that is singled out primarily for its highly valuable wood pattern. Its high commercial demand and its prolonged, intensive, often uncontrolled exploitation, however, have caused a dramatical decline in Karelian birch resources in the second half of the 20th century, putting its very existence in many countries, including Russia, at risk. The features of its reproduction in nature and the advantages of clonal micropropagation for the preservation of the Karelian-birch gene pool and the reproduction of its most valuable genotypes are briefly discussed. We emphasize that, despite the significant interest in the Karelian birch and the vast amount of multifaceted information amassed over years of studies, many questions remain. The authors believe the following issues to be of major importance: (а) the question of its origin, (b) the causes and mechanisms of the formation of its wood-texture pattern, and (c) its taxonomic status. Proceeding from this, we provide a short description of the recent hypotheses that represent the current understanding of these questions, including the authors’ own stance, and a listing of other questions and tasks that could set the directions of further research on the Karelian birch.