Anatomic and morphological description of the sea aster leaves (Aster tripolium L.) on the White Sea coast

The anatomic and morphological description of the sea aster leaves (Aster tripolium L.) of the Asteraceae family is presented in the article. This species is widespread in various plant communities in the intertidal sea zone. The research was conducted within two field seasons (2012-2013) on the Karelian coast of the White Sea in the area that was nominally ecologically clean (in the village of Rastnavolok, 12 km north-west of Belomorsk). In the intertidal zone, along the transect, three test areas were formed from the coast to the water’s edge. The selected areas were characterized by different levels of water column (from 10-20 cm to 50-60 cm) above the plant during flow and flood of various duration (2-3 hours). The coefficient of variation of separate indexes of leaf mesostructure was used to assess plasticity. It indicated that the group of indexes (CV less than 20 percent) - leaf thickness, cell sizes of assimilating tissues (epidermis, palisade and spongy mesophyll), chloroplast quantity - weakly changed within the limits of the studied spectrum of ecotopes and related to the stable characteristics of aster as a secondary water plant. Leaf area, area of stomata and stomatal pores, cell volume are the most varying indexes of mesostructure (CV higher than 20 percent) that enable the species to have high functional plasticity in the wide spectrum of ecotopes of the intertidal zone of the studied coastal ecosystems of the White Sea.