The article describes specific biological traits of Karelian (curly) birch, provides a brief review of various opinions on the causes of its abnormal curly grain. Results of original long-term anatomical-cytological, morphometric and physiological-biochemical studies of the woody species are reported.
A model for controlling the abnormal morphogenesis of the secondary conducting cylinder in woody plants is suggested with Karelian birch as the example. It is demonstrated that: 1) the probable reason for disturbances in the normal rhythm of cambial activity and the ensuring formation of abnormal wood in Karelian birch is excessive sucrose supply to tissues; 2) judging by the patterns in the formation of the assimilatory system of Karelian birch, it appears that the supply of sugars to its stem during the active growth period is much greater than in common birch; 3) the temperature factor must have played an essential part in the origin of this unique form of the downy birch. The applied and basic science aspects are closely interwoven in the results obtained and the conclusions made on their basis. Further investigations along this line hold promise for effective control of morphogenesis processes. Possibilities can thus be created for cultivating woody plants with economically valuable morphological deviations or for eliminating them where necessary.