Scientific publications

Abstract. It is shown that the trunk surface relief of Karelian birch (Betula pendula var. carelica) in the ribbed and ice birch forms is mainly formed by the xylem with normal and curly texture, whereas in the small-knobbed form it is shaped by bark tissues. The xylem with abnormal texture and well developed complex of bark tissue are responsible for the trunk surface relief in the tubercular (with necks and muffs) and knobbed forms. Middle-aged reproductive plants of Karelian birch can be clustered into two big groups depending on the extent and type of bark development. The first group is smooth-barked plants with a relatively thin bark and a ring periderm with a single phellogen layer that consecutively forms phellem (cork) layers – ribbed, ice birch, small-knobbed, and a majority of non-patterned (straight-grained) plants. The second group is plants with a longitudinally–fissured or rhomb-fissured thick bark which forms the rhytidome made up of multiple periderms with non-conducting phloem inclusions – the tubercular and knobbed forms, and a minor part of non patterned (straight-grained) plants. In transitional forms the trunk section with a specific relief correlates with the bark morphology and wood characteristic of that form of the trunk surface.