Glyceria canadensis: first report for Switzerland
In 2020, an unknown species of Glyceria (Poaceae) was recorded very close to the Wachseldornmoos nature reserve which is a protected raised bog area in the central west of Switzerland. In Europe, there are nine native species of Glyceria and one widely distributed hybrid. Only four species are indigenous to Switzerland (G. declinata, G. fluitans, G. maxima and G. notata). The unknown species was subsequently identified as G. canadensis, native to North America, which has been previously recorded from Belgium, Finland, Germany and Great Britian. After a comprehensive survey, two populations of G. canadensis were found in the municipality of Wachseldorn, one inside the nature reserve and one just outside in a drainage ditch. It is estimated that the occurrence of G. canadensis covers a total area of 350 m2. The population inside the nature reserve consists of approximately 350 plants whereas the population in the drainage ditch consists of 800 plants. The pathway for the introduction of the Swiss population is unclear. Previous introductions into the EPPO region may be via a contaminant of used machinery (e.g. military equipment from North America), and as a contaminant of seed. G. canadensis has the potential to compete with vulnerable native plant species and degrade natural habitats. The population in the nature reserve is being controlled.
Sources
Verloove F, Bischoff W (2022) First record of a naturalized population of Glyceria canadensis (Poaceae), another potentially invasive New World grass species, in Switzerland. Wulfenia 29, 28-34.