Wolffia arrhiza found in Sweden, new to the Nordic countries.
The rootless duckweed Wolffia arrhiza has been found at Stjärneholm in Scania, southern-most Sweden. This species, the smallest flowering plant of Europe, was not earlier recorded from the Nordic countries. It has most probably been spread by migrating water fowl from the Low Countries, Germany or perhaps Poland, where it has numerous localities. This paper is dedicated to the memory of prof. dr Elias Landolt (1926-2013), the "grand old man of duckweeds".