Ok, I am not familiar with the Plantain, but yes, the stems are very similar. I had just noted early this year I had some arrowhead transplants that a few never really fully matured (Planted too late) and the leaves didn't fill fully and looked similar to the top photo.
each nutlet trio forms only off of main stem on arrowhead, the Plantain I read about says seed pods will split off of secondary shoots from main stem.
You're most likely correct Bill, I'm not the plant guru I'd like to be.
edit: to the OP, i'd say either plant is good!
