"The portal of the Temple of the Foliated Cross bears a foliated variant of the World Tree formed by a maize plant rising from a band of water and Kan-cross Waterlily Monster, one of the symbols of the watery world of raised fields and swamps.
In the crown of this foliated tree sits a huge water bird wearing the mask of the Celestial Bird. The branches of the tree are ears of maize manifested as human heads, for, in the Maya vision, the flesh of human beings was made from maize dough. This Foliated Cross represented the cultivated world of the community through the symbol of a maize plant rising from the waters of the earth as the source of life.
Maize was not only the substance of human flesh, but it was the major cultigen of the Maya farmer. As the sustainer of life, and as a plant that could not seed itself without the intervention of humans, maize was an ultimate symbol of Maya social existence in communion with nature."
Linda Schele & David Freidel, A Forest of Kings: The Untold Story of the Ancient Maya, p. 243