I spotted this plant on the river bank. I see them often, but not usually on the edge of the river. Wikipedia tells me this plant is notable for its concentrations of two pyridine alkaloids: lobeline and nicotine. It can produce psychoactive effects at small dosages but unpleasant effects at high ones. The sap from the plant is also irritating and can cause blindness. I often see people spraying herbicides in cattle pastures and I imagine this is one of the plants they target.