The group of apophytes (native synanthropic plants) in the Seymskiy Regional Landscape Park (Sumy Oblast, northern Ukraine) has been studied with respect to its species composition and other features. This group in the park includes 285 species from 193 genera and 63 families. Among them, the most numerously represented families are the Asteraceae, Fabaceae, Caryophyllaceae, Poaceae, Scrophulariaceae, Lamiaceae, Rosaceae, Brassicaceae, Apiaceae, Polygonaceae, Boraginaceae, Cyperaceae, and Ranunculaceae, while the major genera are Trifolium, Veronica, Carex, Galium, Poa, Artemisia, Centaurea, Plantago, Potentilla, Rumex, Verbascum, and Viola. This study shows that hemicryptophytes dominate among plant life-forms, and most species are mesophytes. Meadow species of apophytes are the most numerous ecological group. The core of the group of apophytes consists of species of European-West Asian, Eurasian, European, and circumpolar distribution. According to the latitudinal types of distribution range, dominant positions are occupied by temperate-submeridional, boreal-submeridional, boreal-meridional, and temperate-meridional species. Hemiapophytes make up 41.4% of apophyte species, while accidental apophytes (38.2%), and euapophytes (20.4%) are less numerous. In the flora of the park, apophytes prevail over the adventive fraction (alien species introduced accidentally or intentionally). This contrasts with the contribution of apophytes to the flora of Ukraine and other protected areas.