Modern herbalism doesnt employ this much but in Central Texas, it is such a common native plant we may want to relook at it–not just for the pretty flowers.
Here are some great photos http://www.henriettesherbal.com/eclectic/rafinesque/pics/rafin-20-cephalanthus-occidentalis.html
The late great Herbalist Michael Moore terms it a “bitter tonic, and cholagogue”, best for short term use.
I often find buttonbush growing along waterways. The bark and twigs are employed for use in tea or tincture to stimulate digestion. It also seems to be somewhat of a diaphoretic and diuretic, just generally stimulating secretions.
Scenario: you just went to your favorite Tex Mex restaurant and filled up on chips and queso, added in some margaritas and THEN ate dinner–an hour later you are sitting around unable to move with your fly unbuttoned. The next morning, you have gas pain perhaps, but nothing is moving well so to say. Now would be the time for buttonbush–get it? Its for when you eat so much sticky inflammatory food you block up you gi tract and nothing can move, let alone your legs, and you “unbutton” your fly. You could also take a few drops in preparation for such a meal. Bitters like this work in very small quantities–like 10 drops of tincture or just ba swallow or two of tea. Bitters are also contraindicated in the first trimester of pregnancy and many other conditions, so dont go grazing on wild plants before you learn more about them than a short piece on the internet!
I would think about tempering it with the addition of something like Mallow leaf or Chamomile if you have eaten a highly acidic meal, bitters can sometimes be over stimulating(so if you mix in the margaritas you may want to bring in some mucilaginous, antacids)
More information here in Cook’s Dispensatory http://medherb.com/cook/cook.pdf