The comment "Introduced from Europe, is now widely established and included as a native plant in the Pacific Northwest" is contradictory.
An introduced species is NEVER NATIVE. Never can be no mater how long its established or widespread it is....
See the
Wiki definition: "In biogeography, a species is defined as native (or indigenous) to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention."
You may mean
"naturalized" which means the plant is now widespread and reproducing on its own in the wild, after its introduction.
Many do consider it invasive in the USA
http://www.invasive.org/browse...