But I've had no luck using dichotomous keys for either! I'm in zone 7, coastal New Jersey, and these things grow wild everywhere. This one in my yard grew from nothing to four feet high in one year.
Thanks! It's very similar to image searches I'm bringing up with that name, but I've never seen one flower, and all of the plants in this area seem a lot more Suessical in shape, even the very tall ones, compared to the images coming up under that name. Perhaps the soil isn't quite right, this whole area was intensely chemically cleansed from a steel factory's previous damage about 10 years ago.