The distribution of two halophytic species of the genus Spergularia (S. marina and S. media) in the Czech Republic is described based on examination of herbarium material and our own field surveys. Both species have a similar natural distribution, growing only in saline habitats in north-western Bohemia and southern Moravia. They are classified as critically endangered species. Our main goal was to document their expansion in salted road verges and along motorways.
Spergularia marina is frequent in salted verges of motorways and is also found scattered along other roads throughout the Czech Republic, most often in locations higher than 400 m above sea level, where more de-icing salt is used. It also spreads to towns, where it occurs in e.g. the pavements. Spergularia media is much rarer, growing only at four localities in southern Moravia, and has been missing in Bohemia for over 40 years. We also found this species very rarely along roads (5 localities), which contrasts with the expansion of S. marina.