Abstract. The flora of the Thracian Lowland region was analyzed in 13 target localities (seminatural grasslands) near rapeseed fields for a 3-year period. A total of 245 flowering species were registered in the experimental fields, 178 of them were enthomophyllic plant species. Eleven adventitious and invasive species were recorded in representative experimental fields and their margin. The share of adventive species are small percent of the species composition, but pose a future threat to biodiversity. Maintaining the relative naturalness of these areas has a big role in the nutrition for the pollinators. This study provides data about the identification, observation in the field margins. The collected data could be a base for evaluation of the ecosystem services provided by agrocoenoses and neighboring semi-natural grasslands in the Thracian Lowland.