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.

1.  Homer, Odyssey, 10.510. See Pliny, Natural History, 16.46.110: the willow drops its seed before it is absolutely ripe, and for that reason was called by Homer ‘seed-loser’.

2.  The waters of Lake Clitorius in Arcadia generated an aversion to wine in those who drank of them. See Pliny, Natural History, 31.13.16; Ovid, Metamorphoses, 15.322ff. The combination of the two images here may symbolise minds and characters gone to the bad and producing nothing of value. See Erasmus, Parabolae, p. 268: “As willow-seed, shed before it ripens, is not only itself barren but when used as a drug causes barrenness in women by preventing conception, so the words of those who teach before they have truly learnt sense not only make them no better in themselves, but corrupt their audience and render it unteachable”; and p. 230: “Those who have drunk of the Clitorian Lake develop a distaste for wine, and those who have once tasted poetry reject the counsels of philosophy, or the other way round. Equally, those who gorge themselves with fashionable pleasures reject those satisfactions which are honourable and genuine.”