1.  The white poplar was dedicated to Hercules. According to Pausanias, Periegesis, 5.14.2, Hercules introduced it to Greece. According to another story, Hercules on his way back from the Underworld garlanded his head with stems from a white poplar growing beside the Acheron, a memorial of the nymph Leuke (White) carried off by Pluto.

2.  noxque diesque, ‘its dark and light’ (lit. night and day), a reference to the dark green surface and white underside of the white poplar leaf. According to Pliny, Natural History, 16.36.87, the leaves of the white poplar turn over at the summer solstice. Hercules was equated with the sun: Macrobius, Saturnalia, 1.20.6 and 10.