Cardamine occulta Hornem. in Hungary, and other stowaways of the ornamental plant trade

During the study of the weed flora of garden centers in Hungary (among 2017–2020), remarkable populations of Cardamine occulta Hornem., a new alien for the Hungarian flora were found. C. occulta was present altogether in 51 of the 53 visited sites. Dominantly the regularly irrigated and continuously moist microhabitats (pots, containers, muddy surfaces of geotextile-covered beds etc.) were colonized. During the revision of our recently collected specimens, deposited in JPU and DE herbaria as Cardamine hirsuta L., further individuals proved to identical with this till overlooked species. One of them (27.08.2004., Heves county: Eger [8088.3; 8188.1], coll. by A. Schmotzer, deposited in DE collection) proved to the third documented occurrence in Europe, comparing to the accessed literature data. Eclipta prostrata (L.) L. and Urtica membranacea Poir. are also new aliens for the Hungarian flora. Several introduced individuals of these taxa were found in containers of imported thermophilous woody ornamentals at 4 and 2 sites, respectively. Tens of individuals of Eclipta prostrata were also found in a sapling-bed at another site. New populations of scarce or rare Euphorbia prostrata Aiton, E. serpens Kunth and Veronica peregrina L. were also documented.