Sentence:  They [the Aztecs] considered the plant sacred and it played a key role in many rituals. The Catholic Spaniards were particularly disturbed by the practice of mixing a little blood from human sacrifices into <WSD>amaranth</WSD> dough, baking it into cakes which were then broken up and eaten by the faithful. [...] In the nineteenth century there were reports of rosaries being made out of the stuff, and popped <WSD>amaranth</WSD>, mixed with honey, is still used to make a sweet called "alegria" ('happiness') in Mexico. 
Meaning of the word marked with <WSD> tags:  The seed of these plants, used as a cereal.