Is this a weed?
This plant appeared last year in the space where I had once planted three blueberry bushes that never took off (or so I believe). I cut it back to the ground and planted an azalea bush in the area. This year, the plant is back with a vengeance. I suspect it's a weed, but it's growing so well I hate to dig it out if it's not. Any idea what it is? It is really crowding out the azalea.
Allegheny County Pennsylvania
It is an ash seedling and needs to be pulled. Identified based on: opposite, oddly pinnate leaflets.
I'm assuming there are many other in the surrounding area?
No, there aren't many that I've noticed. It is growing quite fast, and is double now than when I took the photo on 5/26. I'm attaching another photo of the woody stems. At this point I will lop it to the ground and dig up the roots since it's beyond pulling.
That would be the correct thing to do with the removal of the roots. I spent a whole summer pulling up baby ash trees and continue to pull them up in my backyard.