pezo.

a medicinal herb, something like a thistle, that grows in temperate climates, such as Michoacan; believed to be useful for the chest and comforts the stomach

The Mexican Treasury: The Writings of Dr. Francisco Hernández, ed. Simon Varey, transl. Rafael Chabrán, Cynthia L. Chamberlin, and Simon Varey (Stanford: Stanford University Press, 2000), 139.