Home – Home – Jornals – Flora and Vegetation of Asian Russia 2018 number 4

The systematic composition of the genus Populus L. and its sections has by now remained controversial. Th e traditional application of methods of comparative morphology does not always allow us to identify stable features for the delimitation of taxon. This work presents studies of the anatomical and topographical structure of the petioles of leaves and the distribution of stomata on the leaf blade of the species of the Tacamahaca section common in the northern latitudes, including the disputed East Asian taxon P. koreana , P. suaveolens and P. maximowiczii . Th e most important signs for diagnosing and identifying species of balsamic poplars are: the shape of the cross-section of the petiole in the upper part and the contour of its adaxial side. In general, the anatomical and topographic structure of the petioles of the species of the Tacamahaca section is very similar. They are characterized by: the development of a continuous layer of an angular-lamellar collenchyma under the epidermis, which has a relatively small total cross-sectional area occurs; gradual transition from an angular-lamellar collenchyma to a parenchyma; powerful development of chlorenchyme with large intercellular spaces on the adaxial side; high arched arrangement of the conductive system; the presence of a trough on the adaxial side. Analysis of the epidermis P. maximowiczii , P. koreana and P. suaveolens showed that on the shortened shoots the leaf plates of this taxon are hypostomatic and can not be distinguished by this feature, but they differ in the signs of petyolar anatomy.