I have spent several great sessions working with a volunteer at a park just north of St. Paul treating Japanese knotweed (Fallopia japonica, syn. Polygonum cuspidatum, Reynoutria japonica). This is an amazingly invasive plant. It’s not surprising given it’s a pioneer species on the volcanic desert formed on the southeast slope of Mount Fuji. Here is striking video from the BBC showing the superweed grew more than 1m-tall (3ft) in just three weeks.