Despite these Biblical references to " willows ", whether in Latin or English, the trees growing in Babylon along the Euphrates River in ancient Mesopotamia ( modern Iraq ) and named " gharab " in early Hebrew, are not willows ( " Salix " ) in either the modern or the classical sense, but the Euphrates poplar " ( Populus euphratica ), " with willow-like leaves on long, drooping shoots, in the related genus " Populus ."