 It is named after an Alabama plantation owner, Colonel William Johnson, who sowed its seeds on river-bottom farm land "circa" 1840.The plant was already established in several US states a decade earlier, having been introduced as a prospective forage or accidentally as a seedlot contaminant.A genetic study employing microsatellite markers has investigated Johnsongrass populations across 12 states and confirmed that the weed was introduced to US from Alabama and North Carolina.