Asclepias syriaca in Lithuania
Asclepias syriaca (Apocynaceae) is a perennial herb native to North America, and in the EPPO region it is an invasive alien plant and a species of Union concern (EU Regulation 1143/2014). It was introduced into the EPPO region as a garden ornamental and has since become a problematic species negatively impacting biodiversity and ecosystem services. In the boreal biogeographic region of Europe, A. syriaca has been recorded in Sweden and recently in Latvia. In Lithuania, A. syriaca was first recorded in cultivation in 1930 and it was first recorded in the natural environment in 1991. Until 2015, 7 established populations of A. syriaca had been recorded. Following surveys between 2018-2020, an additional 31 populations were identified, and most populations were located in the southern, eastern, and northeastern parts of the country. Population size generally varies from small (occupying up to 20 m2) to larger stands (up to 500 m2). However, some stands were very large, with the largest known stand present near Meškučiai village which occupied 7390 m2 in 2018. When this latter site was first discovered in 1994, the stand occupied 2130 m2. Thus, in 24 years the size of the stand increased by 5260 m2. In Lithuania, A. syriaca commonly invades anthropogenic herbaceous vegetation and unmanaged xeric grasslands. Some populations have been seen to spread into arable land.
Sources
Gudžinskas Z, Petrulaitis L, Taura L (2021) Asclepias syriaca L. (Apocynaceae) and its invasiveness in the southern part of the Boreal region of Europe – evidence from Lithuania. BioInvasions Records 10 (In Press).