Inventory of the urban flora of Budapest (Hungary) highlighting new and noteworthy floristic records.

Background: The systematic urban floristic research of Budapest was started in 2018 by the authors with detailed methodology. One scope of the research was to gain knowledge on the plant taxa appearing in Budapest and to compile the inventory of the urban flora of Budapest. New information: We have provided the inventory of the urban flora of Budapest, which includes distribution data for all 973 taxa found in Budapest between May 2018 and May 2023. We also provided new detailed occurrence data for 49 species in Budapest. Seven of them are new to the adventive flora of Hungary (Campanulaportenschlagiana Roem. & Schult., Clinopodiumnepeta (L.) Kuntze, Chasmanthiumlatifolium (Michx.) H.O.Yates, Cyrtomiumfortunei J.Sm., Linariamaroccana Hook.f., Talinumpaniculatum (Jacq.) Gaertn.), three were rediscovered in Hungary (Glebioniscoronaria (L.) Cass. ex Spach, Lagenariasiceraria (Molina) Standl., Sisymbriumirio L.) and 18 were recorded for the first time in Budapest. We also provided data for two data-poor (Artemisiascoparia Waldst. & Kit., Polygonumrurivagum Jord. ex Boreau) species and we documented the major expansion of six species.

Methodology of the habitat classification of anthropogenic urban areas in Budapest (Hungary).

The vast majority of floristical and coenological studies focus on the natural vegetation and its remnants in urban environments; however, there is an increasing interest in the systematic exploration of built environments. This survey of the inhabited areas of Budapest launched in 2018 applied a new and detailed methodology. The territorial units of the survey were street sections, where the presence of vascular plants was recorded in ecologically different habitats separately. We laid down the foundations to establish new habitat categories for the habitat classification and mapping of urban ecosystems using a different approach than the Hungarian habitat classification system (ÁNÉR). The method enables us to study the flora of urban ecosystems in detail. We established 18 urban habitat categories, surveyed more than 27,000 survey units and registered 647 spontaneously growing plant species in Budapest. Our survey evinced the spontaneous occurrence of 193 alien species in Budapest, 81 of them are data deficient, while 10 of them are new introductions in Hungary. 53.9% of the aliens are cultivated frequently in Hungary.