Ambitious is an understatement. It can tunnel under rocks and pop out the other side. The roots can embed in landscape fabric. If only deer found it tasty. :)

Please help out the Trillium. Otherwise it's doomed.

Hopefully the trillium, jack in the pulpit and ferns will make it. Did a lot of careful digging and pulling and more digging and more pulling around them and it seems to have discouraged the beast for the most part. Should've taken a photo later in the season. Anxious to check it out in the spring.

Update: Trillium, JIP and ferns doing well, but repeated digging and pulling around them are a must. Since its efforts to engulf the wildflowers for the most part have been thwarted, the goutweed has retaliated by spreading to other areas, despite repeated digging, pulling, trimming, even resorting to spraying those other areas. The battle continues.

It might be easier to remove the keepers, rinse the roots well to make sure there are no goutweed roots being moved, and smother the whole area.