( Others ( ( may ( have ( been ( smaller ( , ( understory plants ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Others)) (VP (MD may) (VP (VB have) (VP (VBN been) (NP (JJR smaller) (, ,) (JJ understory) (NNS plants))))) (. .)))
Others may have been smaller, understory plants.
(ROOT (S (NP (NP (DT The) (NN understory)) (PP (IN of) (NP (DT the) (NN rainforest)))) (ADVP (RB commonly)) (VP (VBZ has) (NP (NP (NNS ferns)) (CC and) (NP (JJ other) (NN ground) (NNS plants)))) (. .)))