I would love to know what you find out.* Let me know if you call the Chicago Botanic Garden too.* I'll bet they'll tell you if their's is sprouting now.
The only thing I can think of is the beds where they were planted were too wet over the winter.* I didn't have much success with them in my garden and finally gave up.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.