 The double color, Servius says, made a wreath that represented the duality of the hero's labors in both the upper and the underworld.The association of white poplar leaves with Herakles is also attested by archaeological remains, such as the poplar-leaf motif carved on a statue base found in a small sanctuary to Herakles (Roman Hercules) along the Tiber river.It has been suggested that behind the vague outlines of this tale lurks an older myth having to do with Herakles' encounter with the river deity Achelous, who had chthonic associations and whose name was the subject of speculative theological etymology among the Greeks, in this case involving "acherōïs", another Greek word for "poplar."