You are probably right about it being pokeweed. It's a perennial and I have one that grows up behind the climbing rose and trumpet honeysuckle trellis against the house. It reaches up to and grows over the first story eave and the trunk (yeah I think you would call it trunk) gets to be about 2" in diameter. I let it weather through the winter and I still have to cut the dead trunk with a saw in spring before new growth starts.
It's a monster but somehow, it's not affecting the rose or the honeysuckle which both compete with the poke to reach up and over the eave
(maybe even keeping the honeysuckle in check).
Pairs and families of cardinals along with other berry loving birds like robins, mockingbirds, and catbirds flock to it when the berries are ripe and pick it clean in no time at all.