( Weeds ( ( ( are simply ) ( ( those plants ) ( that ( grow ( where ( they ( ( are not ) wanted ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Weeds)) (VP (VBP are) (ADVP (RB simply)) (NP (NP (DT those) (NNS plants)) (SBAR (WHNP (WDT that)) (S (VP (VBP grow) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (VBP are) (RB not) (VP (VBN wanted)))))))))) (. .)))
Weeds are simply those plants that 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)))) (. .)))