Nat. Ord. (Natural Order) Salicaceï¿½. Lin. Syst. (Linnean System) Diï¿½cia, Octandria. Arbor Populi, or the people's tree, was the name given in the ancient days of Rome to this tree, as being peculiarly appropriated to those public places most frequented by the people: some ingenious authors have still further justified the propriety of the name, by adding, that its trembling leaves are like the populace, always in motion.