Plant ID – Help?

Plant ID – Help?

I have UGO (Unidentified Growing Objects) in one of my wildflower beds that are actually returning guests. They grew last year and I tried to ID them, but had no luck. I've noticed they're back with a vengeance this year. I took the following pictures last year at the height of the growth. Image hosting by Photobucket Image hosting by Photobucket Image hosting by Photobucket As you can see, by the end of the summer, they became monsters. They never developed flowers, only leafy green roundish heads on top of very tall, sturdy stalks with slender leaves. Each year, I have surprise wildflowers pop up in my mini meadow and I was hoping this would turn out to be a flower, but I'm thinking it's some type of awful weed I'm allergic to (it's happened before with ragweed, so now I'm paranoid). I'm located in north TX, zone 8. Any help would be greatly appreciated. I need to know whether or not to pull these babies out before I sow my spring wildflower seeds. Many thanks in advance.
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