( So ( ( any plant ) ( ( can ( be ( ( considered ( a weed ) ) ( when ( it ( is ( growing ( where ( it ( ( is not ) wanted ) ) ) ) ) ) ) ) ) ) ; ) ) )
(ROOT (S (CC So) (NP (DT any) (NN plant)) (VP (MD can) (VP (VB be) (VP (VBN considered) (NP (DT a) (NN weed)) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBZ is) (VP (VBG growing) (SBAR (WHADVP (WRB where)) (S (NP (PRP it)) (VP (VBZ is) (RB not) (VP (VBN wanted)))))))))))) (: ;)))
So any plant can be considered a weed when it is growing where it is 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)))) (. .)))