Goldenrod, Himalayan balsam, Chinese windmill palm: three plants, one problem. All are native to continents other than Europe, but were introduced to Switzerland as garden or ornamental plants. At some point they "escaped" into the wild, where they now threaten the native flora.
This phenomenon isn't limited to Switzerland: biological invasions happen on every continent every day. A major driver of this is global trade, which is increasingly shifting to the internet and being conducted on auction platforms like eBay. As a result, one click is all it takes to spread potentially invasive plants from continent to continent - and unintentionally encouraging biological invasions.
Monitoring online auctions