( Plant-Eater ( -- ( mainly ( ( eats plants ) . ) ) ) )
(ROOT (S (NP (NNP Plant-Eater)) (: --) (ADVP (RB mainly)) (VP (VBZ eats) (NP (NNS plants))) (. .)))
Plant-Eater -- mainly eats plants.
(ROOT (S (NP (DT The) (NN heterotroph)) (VP (VBZ eats) (NP (UCP (ADJP (JJ only)) (CC or) (ADVP (RB mainly))) (NNS plants))) (. .)))