Architecture of Thymus L. (Lamiaceae) species of Asia

Abstract

The application of the architectural approach makes it possible to determine the features of the morphological structure of plants and their changes when modeling scenarios of environmental impact on the structure of plants. Using an architectural approach, 56 species from the genus Thymus, distributed in Siberia, Primorsky Region and Central Asia, were analyzed. For the first time, within the framework of this approach, an original method of distinguishing an architectural unit in the structure of dwarf shrubs and dwarf subshrubs has been developed. The architectural unit is a branched sympodial axis and has in its composition lateral sympodial axes of n+1 order, formation shoots, branching shoots, ephemerous shoots. It is established that the architectural unit is unchanged in all studied Asian species. The wide distribution of species and their development of contrasting habitat conditions is due to the variety of sympodial axes and shoots that are part of the architectural unit. Depending on the method of axis growth, architectural units with basally and acrosympodially increasing axes are distinguished. They determine the formation of dwarf shrub and dwarf subshrub. According to the direction of growth of the axes, architectural units are distinguished: orthotropic, plagiotropic and mixed type. It has been established that the structure of mature individuals of Thymus is formed due to the repeated repetition of the same or different architectural units. There are 3 variants of the combination of such architectural units in the structure of dwarf shrubs and 4 in the structure of dwarf subshrubs. It is shown that each of the combination variants determines the type of biomorph (monocentric, sparse polycentric, dense polycentric) and depends on the conditions of the ecotope. The revealed modifications of the architectural unit and their combinations determine the development strategy of dwarf shrubs and dwarf subshrubs of Thymus species in the development of Asian conditions.