Flora of the Troyeruchitsa state reserve (Tver oblast, Russia)

The flora of vascular plants of the Troyeruchitsa State Nature Reserve and three surrounding settlements was studied. In 2016-2019, I recorded 489 species of native and alien plants on an area of 10 km2 (supplemented with 12 species from papers published earlier) were revealed, including 456 species growing within the reserve and 45 species along its borders. An annotated checklist of the flora is presented. All known locations are given for species known from 1, 2 or 3 localities. Three species ( Erigeron × huelsenii , Eupatorium purpureum , Rumex × heterophyllus ) are novelties to the flora of Tver Oblast. Six native species are new to the flora of Ostashkovsky District ( Monotropa hypophegea , Plantago uliginosa , Rosa × majorugosa , Rubus nessensis , Sparganium gramineum , Typha angustifolia ) as well as 19 species of alien plants. Sixteen species from the Red Data Book of Tver Oblast and four species from the Red Data Book of the Russian Federation are reported from the reserve. A dataset of georeferenced photos uploaded on iNaturalist as part of the Troyeruchitsa Local Flora project (https://www.inaturalist.org/projects/lokalnaya-flora-troeruchitsa) encounts 434 observations of 358 species. High diversity of flora is the most important feature of the area.