I should do some searches first, but I'm tired: I think there's a midwest
native Rhamnus, a WI marsh shrub. I don't think it's very common. If we get
more floods maybe its habitat will expand. Anybody growing this for fruit?
Given the ability of the native R. purshiana to grow and spread here in
Oregon, it's very easy to understand how a related species could be a weed
elsewhere. Birds spread them readily and they are vigorous stump sprouters,
so cutting them doesn't kill them. There is still some use of the bark,
Cascara, famous as a laxative.