You sure the last pic is the same plant as the others? The leaves look entirely different. The first couple pics remind me of ironweed.....I have said that on some other threads recently so maybe I just have it on the brain. Ironweed at my place is flowering currently and it produces a very purple flower, but I understand there are various types of iroweed as well (as Native Hunter explained in another thread/forum). Like I said - unless I am looking at the wrong thing....I am not sure the last pic is the same plant.