A dataset contains more then 31,000 unique occurrences of 786 vascular plant species from Udomlya district of Tver Oblast (Russia). They are based on field studies, performed on basis of the “Lake Moldino” biological station of Moscow High School # 1543 in 2007–2016 by numerous teachers and students (principal investigators Liudmila A. Abramova and Polina A. Volkova). Georeferences are based on 105 squares 5 km × 5 km (occurrences are placed in the grid square centroids). Several squares were investigated twice; results of both surveys are given separately, so some records are duplicated (if a species was recorded during both surveys of one square). The analysis of the dataset has been published by Volkova et al. (2016; 2018).