herbivorous

from WordNet (r) 3.0 (2006)

herbivorous
    adj 1: feeding only on plants [ant: {carnivorous},
           {insectivorous}, {omnivorous}]

from The Collaborative International Dictionary of English v.0.48

Herbivorous \Her*biv"o*rous\, a. (Zool.)
   Eating plants; of or pertaining to the Herbivora.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

36 Moby Thesaurus words for "herbivorous":
      cannibal, cannibalistic, carnivorous, commensal, dietetic, dining,
      eating, feeding, flesh-eating, fruitarian, gastronomic, gluttonous,
      grain-eating, graminivorous, granivorous, grass-eating,
      insect-eating, insectivorous, lactovegetarian, man-eating,
      meat-eating, mensal, nourishing, nutritious, omnivorous,
      omophagous, pantophagous, phytivorous, phytophagous, plant-eating,
      postprandial, prandial, predacious, preprandial, vegetable-eating,
      vegetarian