What plant covered the Asphodel Meadows in the Greek underworld?

The plant associated with covering the Asphodel Meadows was asphodel.

The Asphodel Meadows were a region of the Greek Underworld where many ordinary dead were said to dwell. Their name comes from asphodel, a group of Mediterranean plants in the genus Asphodelus. In Homeric tradition, the meadows appear among the landscapes of the afterlife, and later writers connected the pale, ghostly flowers with graves, mourning, and the dead.

The plant is not necessarily a single precisely identified species. Modern discussions have proposed white asphodel, especially Asphodelus albus, while other interpretations suggest that ancient descriptions may have included related species or even narcissus. Nevertheless, “asphodel” is the standard mythological answer and the source of the meadow's name.

The meadows were not identical to Tartarus, the place of punishment, or Elysium, the blessed destination reserved for favored souls in many later accounts. They represented a more ordinary afterlife. Homeric and post-Homeric descriptions also changed over time: early references can seem shadowy and bleak, while later poets portray the fields as more beautiful and flower-filled.