( ( ( The ( stem tubes ) ) ( that ( transport ( ( ( the water ) and ) ( other nutrients ) ) ) ) ) ( ( up ( into ( the plants ) ) ) ( ( are ( ( the structures ) ( ( called xylem ) ( while ( ( ( the ( stem tubes ) ) ( that ( ( carry ( the food ) ) ( ( back down ) ( to ( the plant ) ) ) ) ) ) ( is ( called ( the phloem ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (DT The) (NN stem) (NNS tubes)) (SBAR (WHNP (WDT that)) (S (VP (VB transport) (NP (NP (DT the) (NN water)) (CC and) (NP (JJ other) (NNS nutrients))))))) (ADVP (RB up) (PP (IN into) (NP (DT the) (NNS plants)))) (VP (VBP are) (NP (NP (DT the) (NNS structures)) (VP (VBN called) (NP (NN xylem)) (SBAR (IN while) (S (NP (NP (DT the) (NN stem) (NNS tubes)) (SBAR (WHNP (WDT that)) (S (VP (VBP carry) (NP (DT the) (NN food)) (ADVP (ADVP (RB back) (RB down)) (PP (TO to) (NP (DT the) (NN plant)))))))) (VP (VBZ is) (VP (VBN called) (NP (DT the) (NN phloem))))))))) (. .)))
The stem tubes that transport the water and other nutrients up into                           the plants are the structures called xylem while the stem tubes that carry the food                           back down to the plant is called the phloem.
(ROOT (S (NP (NNS Stems)) (VP (VBD transport) (NP (NN water)) (PP (TO to) (NP (NP (JJ other) (NNS parts)) (PP (IN of) (NP (DT the) (NN plant))))) (PP (IN through) (NP (NP (DT a) (NN system)) (PP (IN of) (NP (NNS tubes)))))) (. .)))