Lepidium oblongum (Brassicaceae) appeared on Hungarian railways: the beginning of a wider European conquest?
Lepidium oblongum, of American origin is a new member of the European adventive flora, only detected in Romania so far. The first Hungarian stand was discovered in 2018, and others in 2020. Based on our studies, we detail its morphological characteristics in comparison with other Lepidium species. We present a new drawing and a table to help identify the species. Lepidium oblongum is easily identifiable by its divided (lobed or lobed-dentated) upper stem leaves. By analyzing selected climatic parameters we show that the new European habitats are found in the drier and cooler summer subtype of the humid continental climate belt. In Hungary, it spreads directly along the railways. The establishment of individual populations can be influenced by the location of cargo unloading and the movement of railway workers. Lepidium oblongum occupies gravelly, sun-exposed habitats along Hungarian railway tracks such as loading platforms, guardhouses and goods stations. Based on its high stress and climatic tolerance and initial spreadrate, it is consider to be a naturalized member of the European adventive flora, that could be potentially invasive along the European railways.