Persephone, Goddess of Spring & Nature, taken by Hades to become Queen of the Underworld , ate the pomegranate seeds & having tasted the food of the underworld was obliged to spend a third of each year (the winter months) there, and the remaining part of the year with the gods above.  When Persephone was reunited with her mother Demeter, the Earth flourished with vegetation and colour, but for some months each year, when Persephone returned to the underworld, the earth once again became a barren realm.