Architectural modifications that allowed Thymus marschallianus to spread widely in Central and North Asia

In the conditions of climate change, when some plant species are completely disappearing, and others are forced to adapt quickly, it becomes extremely important to find the main architectural characteristics that allow plants to spread to new territories. This study demonstrated the modifications of the architecture of Thymus marschallianus and its relationship with the environmental conditions of Central Asia (Kazakhstan and Kyrgyzstan) and North Asia (Russia). For the first time, we tried to combine architectural and eco-morphological approaches to studying plants, which allowed us to obtain the most complete information about the morphological mechanisms of plant adaptation. The diversity of shoots and categories of axes (monopodial system of shoots and sympodial axis) were identified. The variability of monopodial system of shoots and sympodial axis modify the architecture of T. marschallianus. We characterized three modifications of this architecture and established their relationship with specific habitats. We found out that the basitonic branching of the monopodial system of shoots determines life form (dwarf subshrub), and the growth direction of the sympodial axes determines growth form (prostate or erect). The differences in architecture, growth forms and quantitative characteristics of sympodial axes are related to environmental conditions, particularly the cover of herbaceous plants, dead grass, and stones, as well as topography. We propose that the morphological variability of T. marschallianus allowed this species to spread widely in the plains and mountains of Central and North Asia.