I live in Clackamas county, West Linn. A large new plant has come to my attention.This monster first appeared on my hillside last year and I cut it down. This summer it has reappeared, growing to 15' + height with huge leaves 18-20" across. Research on the internet leads me to believe it is Paulownia elongata, although I first considered it a Velvetleaf, it produces no flower or seed. Now why I am inquiring is that I am noticing this plant in ditches and parks in the community. Do you believe there is any concern for this plant?
Thank you for choosing Ask an Expert for help with this fast-growing tree. I suspect that it is a Paulownia. The Paulownia tomentosa is the species most likely to be seen in our area. It is definitely considered an invasive species, undesirable due to its fast-growth, preference for disturbed, untended sites, and ability to spread thousands of seeds each year. This is why you have noticed it growing widely.
This is not a tree that environmental agencies, city foresters, or nurseries would recommend you plant. That said, many people have them in their yards and appreciate the shade they give and the flower display in spring. You would have to wait until the tree is more mature for it to flower. It will grow to 60 feet or more, though it can be cut to the ground each fall to re-grow to a shorter height each summer. Grown this way, the plant does not go to seed and wouldn't become a pest to others.
For more information on this tree, and some images, see the Oregon State University Landscape Database, here: https://landscapeplants.oregonstate.edu/plants/paulownia-tomentosa
Have a good fall,