The structure of the needles mesophyll at species of the Pinaceae family

Comparative study of the structure of the needle mesophyll and the diversity of assimilatory cell forms at 27 species from 7 genera (Abies, Tsuga, Pseudotsuga, Picea, Pinus, Cedrus, Larix) of the Pinaceae family was carried out. The researches were carried out under a light microscope using macerated preparations, as well as on transverse, paradermal and radial sections of the middle part of the needles. Among the cells of complex shape, flat cellular cells located along the needles, flat folded cells, the main projections appearing on the transverse sections, and more complicated folded-cellular, combining lobed outlines in the cross-section and cellular in the longitudinal direction, were distinguished. The genera of Pinaceae under consideration can be divided into two groups according to the structure of the assimilatory tissue of needles by the presence or absence of cells of complex shape, in connection with which the prevailing types of mesophyll for each genus are distinguished and characterized in more detail. It is shown that within the separate genera of the Pinaceae family, the characteristic features are observed in the structure of the needles mesophyll, which may also be partly due to the presence of different variants of cells of complex cellular and folded forms.