( ( In agriculture ) ( , ( plants ( ( ( are now ) ( ( called crops ) ( if ( they ( ( are ( ( useful and ) weeds ) ) ( ( ( if ( they ( ( are not ) useful ) ) ) or ) ( if ( they ( grow ( where ( they ( ( are not ) wanted ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NN agriculture))) (, ,) (NP (NNS plants)) (VP (VBP are) (ADVP (RB now)) (VP (VBN called) (NP (NNS crops)) (SBAR (IN if) (S (NP (PRP they)) (VP (VBP are) (ADJP (JJ useful) (CC and) (JJ weeds)) (SBAR (SBAR (IN if) (S (NP (PRP they)) (VP (VBP are) (RB not) (ADJP (JJ useful))))) (CC or) (SBAR (IN if) (S (NP (PRP they)) (VP (VBP grow) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (VBP are) (RB not) (VP (VBN wanted)))))))))))))) (. .)))
In agriculture, plants are now    called crops if they are useful and weeds if they are not useful or if they grow where they are not wanted.
(ROOT (S (NP (NP (NNS Plants)) (SBAR (WHNP (WDT that)) (S (VP (VBP grow) (SBAR (WHADVP (WRB where)) (S (NP (PRP you)) (VP (VBP do) (RB n't) (VP (VB want) (NP (PRP them)))))))))) (VP (VBP are) (VP (VBN called) (NP (NNS weeds)))) (. .)))