Ἄγνον

They are not speaking of the lugos.¹ And Chionides uses it in the masculine in Heroes: "and verily, by Zeus, I don't seem anymore to be different from an agnos growing in a mountain stream."² Plato [writes]: "for this plane-tree [is] very wide-spreading and lofty, and the height and the shade of the agnos [are] gorgeous."³
But hagnos with the accent on the final syllable [means] pure.