Distribution and chromosome number of Sonchus palustris in Slovakia

The distribution of Sonchus palustris in Slovakia was studied using herbarium specimens and literary sources. The herbarium studies, supplemented with targeted field search in the years 2015–2018, revealed 61 new localities and confirmed many other older locations. The species has been recorded in 19 phytogeographical districts and sub-districts of Slovakia. Most of the records are concentrated in the Podunajská nížina lowland in SW Slovakia and in the Ipel'sko-rimavská brázda region in southern Slovakia. Our results showed that the species is relatively common in different types of wetlands and its re-evaluation in the recent version of the Slovak red list is not needed. Chromosome number data for two new populations in eastern Slovakia (both 2n = 18) were counted. The distribution map is given.