Understanding the drivers of invasive species’ success is essential for predicting and managing their ecological impacts. Symphyotrichum squamatum, a South American species first recorded in Bucharest in 2015, is currently expanding into urban and peri-urban areas of Romania, raising concerns about its invasive potential. This study provides a comprehensive assessment of its invasiveness by integrating species distribution modeling, a reproductive trait analysis, and morpho-structural evaluations. To deepen our understanding, we compare S. squamatum with S. ciliatum, a species already invasive in Romania, to identify shared traits potentially driving their invasiveness. Using R software (version 4.3.0) with bioclimatic variables, we modeled the potential distribution of both species. The reproductive success of S. squamatum was evaluated through germination tests on seeds from distinct Romanian populations, while anatomical analyses revealed adaptations potentially linked to invasiveness. Our findings indicate that S. squamatum shares traits with successful invaders, as highlighted by its comparison with the invasive S. ciliatum. However, its expansion in Romania appears to be constrained by environmental factors, with continentality emerging as a key determinant influencing the distribution of both species. This study highlights the importance of combining ecological modeling with trait-based analyses to assess invasive potential, offering a robust framework for managing alien species.

Numerous ornamental plant species introduced to Europe have become invasive. Asclepias syriaca L. is a notable example and the focal point of our research. Native to North America, it was introduced to Europe in 1629 and is currently listed as an invasive species of concern under EU Regulation 1143/2014. In Romania, the species was first reported in 1836. Asclepias syriaca demonstrates a high capacity to adapt to various climatic and edaphic conditions. In Europe, it primarily inhabits abandoned agricultural lands, wet and dry meadows, road edges, and tree plantations, negatively impacting agriculture. The species exhibits competitive traits such as height, shad e tolerance, vegetative propagation, drought resistance, and allelopathic potential. The aim of this study was to investigate the ecological and anatomical characteristics contributing to the invasive potential of Asclepias syriaca in Romania. The analyses of the current state of the species’ populations highlighted the environmental conditions that support its establishment and spread. Additionally, anatomical investigations revealed structural traits that further emphasize its adaptability to diverse envi ronmental conditions. This study enhances our understanding of the ecology and adaptive capacity of Asclepias syriaca , with significant implications for managing ecosystems affected by this invasive species in Romania.