Knowing that almost 40% of the invasive plants now in the US were brought in initially as horticultural plants, it’s no surprise that LIISMA has an astonishing number of tier 5 invasive plants (460 according to our records). If you’re not familiar with the New York State PRISM tier ranking system for invasive species prioritization, a tier 5 invasive species is one that is already found in a given area, but requires more information on its spread and ecological impact. Two such plants on this section of the tier list are tea Viburnum (Viburnum setigerum) and linden viburnum (Viburnum dilatatum).