( ( ( ( The ( ( structure and ) formation ) ) ( of ( the ( cell wall ) ) ) ) ( in xylem ) ) . )
(ROOT (NP (NP (DT The) (NN structure) (CC and) (NN formation)) (PP (IN of) (NP (DT the) (NN cell) (NN wall))) (PP (IN in) (NP (NN xylem))) (. .)))
The structure and formation of the cell wall in xylem.
(ROOT (S (NP (DT A) (NN cell) (NN wall)) (VP (VBZ is) (RB not) (ADJP (JJ present) (PP (IN in) (NP (NN animal) (NNS cells))))) (. .)))