gramineous adj.

1650s, from Modern Latin gastricus, from Greek gaster (genitive gastros) "stomach, paunch, belly," often figurative of gluttony or greed, also "womb, uterus; sausage," by dissimilation from *graster, literally "eater, devourer," from gran "to gnaw, eat," from PIE root *gras- "to devour" (source also of Greek grastis "green fodder," Latin gramen "fodder, grass," Old English cærse "cress").

"feeding on grass," 1739, from gramini-, combining form of Latin gramen (genitive graminis) "grass, fodder" (see gramineous) + -vorous "eating, devouring."