( ( ( ( plant size ) , ) ( stem structure ) ) ; )
(ROOT (NP (NP (NN plant) (NN size)) (, ,) (NP (NN stem) (NN structure)) (: ;)))
plant size, stem structure;
(ROOT (S (NP (DT The) (NN stem)) (VP (VBZ is) (NP (NP (DT the) (JJ basic) (NN structure)) (SBAR (WHNP (WDT that)) (S (VP (VBZ holds) (S (NP (NNS plants)) (ADJP (JJ upright))) (, ,) (S (VP (VBG allowing) (NP (NNS plants)) (S (VP (TO to) (VP (VB get) (NP (NP (DT the) (NN sunlight) (CC and) (NN air)) (SBAR (S (NP (PRP they)) (VP (VBP need))))))))))))))) (. .)))